This lecture was given in February, 2014 as part of the California native plant gardening series ‘Out of the Wilds and Into Your Garden’

1. Out of the Wilds and Into Your Garden
Gardening with Western L.A. County Native Plants
Project SOUND – 2012 (our 8th year)
© Project SOUND

2. Botany for S. CA
Gardeners
Key Botanic Concepts to
Improve Your Gardening
C.M. Vadheim and T. Drake
CSUDH & Madrona Marsh Preserve
Madrona Marsh Preserve
February 1 & 4, 2014
© Project SOUND

3. California – the land of extremes





Latitude
Elevation
Temperature
Precipitation
Soil type, content
That’s part of the reason why
my have so many unique
native plants
http://mapsof.net/uploads/static-maps/california_relief_map.png
© Project SOUND

4. Botany: the study of plants (huge subject area)
Today’s talk
I. Names, descriptions and taxonomy
II. Seeds
A.
B.
C.
How they develop
Dispersal
Germination
III. How plants grow
IV. Water & nutrients from the
environment
© Project SOUND

5. Hollyleaf Redberry – Rhamnus ilicifolia
© 2003 BonTerra Consulting
© Project SOUND

6. Scientific names: why do we need ‘em?
 They are (or at least should be)
universal
 They are unique to a given taxon –
unlike common names like ‘Wild
pea’ or ‘Wild sunflower’
 The name sometimes describes
characteristics of the plants
[ilicifolia = holly-like leaves] or
honors the person who discovered
them
© 2006 Steve Matson
 The name (should) reflect the
evolutionary relationships
between it and other taxa
Rhamnus ilicifolia
© Project SOUND

7. Taxonomy & Systematics: grouping & naming
 Taxonomy: science that finds,
identifies, describes, classifies,
and names plants
 Three goals:
 Identification : identifying an
unknown plant by comparison
with previously collected
 Classification: placing known
plants into groups or categories
to show some relationship.
 Description : formal description
of a new species, usually in the
form of a scientific paper
 Systematics: the science of
relationships between plants
and their evolution, especially
at the higher levels
 Classical (morphological)
systematics – based on
similarities in plant physical
characteristics (how plant
looks; chemical similarities;
etc.)
 Molecular systematics –
based on similarities in
genetic material
The two are highly interrelated – both aim to better understand and
reflect the true relationships between different plants
© Project SOUND

8. http://seinet.asu.edu/images/vasc_herbarium_images/Rhamnaceae/photos/Rham_croc_SL_N0086.jpg
Kingdom
Subkingdom
Superdivision
Division
Class
Subclass
Order
Family
Genus
Species
© 2005 James M. Andre
Plantae – Plants
Tracheobionta – Vascular plants
Spermatophyta – Seed plants
Magnoliophyta – Flowering plants
Magnoliopsida – Dicotyledons
Rosidae
Rhamnales
Rhamnaceae – Buckthorn family
Rhamnus L. – Buckthorn
Rhamnus ilicifolia Kellogg – Hollyleaf redberrry
© Project SOUND

9. Resources to help the confused gardener
 USDA Plants Database:
http://plants.usda.gov/java/
© Project SOUND

10. The importance of higher taxa: insight
 Family Rhamnaceae
© 2005 James M. Andre
© 2003 BonTerra Consulting
 Mostly trees/shrubs
 Simple leaves, with stipules
 Flowers usually small, inconspicuous
[exception: Ceanothus spp.]
 Fruits are mostly berries, fleshy
drupes or nuts – mostly dispersed
by mammals and birds.
 Chiefly used as ornamental plants
and as the source of many brilliant
green and yellow dyes
© Project SOUND

11. The importance of higher taxa: insight
 Genus Rhamnus
© 2002 Kristiaan Stuart
Spiny redberry
Rhamus crocea
Common name: Buckthorn
Usually deciduous – CA has evergreen species
Fruit: berrylike, fleshy (edible?)
Wide light tolerance range
Generally drought tolerant once established
May be slow to get started – then easy to grow
May cause mild dermatitis
Medicinal: prepared bark - purgative; laxative
Invasive potential: in Eastern U.S., exotic
buckthorns (R cathartica; R. frangula) tend to
form dense, even-aged thickets, crowding and
shading out native shrubs and herbs
 California members:









 Rhamnus (now Frangula) californica – CA
Coffeeberry
 Rhamnus crocea – spiny redberry
http://biology.csusb.edu/PlantGuideFolder/RhamnusCrocea/RhamnusCroceaPage.htm
© Project SOUND

12. The scientific name
 The generic name is listed first
(with its first letter capitalized),
followed by a second term, the
specific name (or specific
epithet) and the name(s) of the
first namer
 International Code of Botanical
Nomenclature – specifies the
format and conventions
 U.S. Integrated Taxonomic
Information System (ITIS) facilitates sharing biologic info.
by providing a common framework
for taxonomic data
Hollyleaf redberry
 Sometimes regional experts don’t
agree with ITIS
Rhamnus ilicifolia Kellogg
© Project SOUND

13. Calflora database: CA plants (native & not)
© Project SOUND

14. What is a species?
 Some definitions of species
 Biological Species Concept - they cannot
interbreed & produce viable offspring;
interbreeding studies
Lyonothamnus floribundus
ssp. aspleniifolius
 Morphospecies Concept - they are
different morphologically and do not
come in contact for interbreeding
 Genetic Species Concept – still working on
this – how similar must they be to
constitute a species?
 Practical definition - Practically,
biologists define species as populations of
organisms that have a high level of
genetic similarity.
 The field of taxonomy is changing with
our increasingly sophisticated tools
Lyonothamnus floribundus
ssp. floribundus
© Project SOUND

15. California (and other biologic ‘hotspots’)
present more challenges
 Lots of geographic/topographic
variability
 Relatively ‘rapid’ environmental
changes (since last Ice Age)
© 2002 Kristiaan Stuart
Rhamnus ilicifolia
 Lots of geographically separate
populations – are in the process of
diverging
 In other words, speciation is a
‘work in progress’
Rhamnus crocea
© Project SOUND
http://biology.csusb.edu/PlantGuideFolder/RhamnusCrocea/RhamnusCroceaPage.ht
m

16. Why all the current taxonomic/systematic
arguments about CA native plants?
 When two species have fully diverged from a common ancestor
they will possess the properties commonly associated with
independent species:
 reproductive incompatibility
 distinctive morphology
 ecological uniqueness.
 During the process of divergence, these properties are
gradually acquired in a continuum spanning thousands of years.
 When two lineages are in the early stages of speciation it is
difficult for biologists holding different species concepts to
agree on when there has been enough divergence to declare
them as different species.
© Project SOUND

17. What’s a CA native plant gardener to do?
 Keep calm – this period of rapid
change will end
 Nurseries will likely know plants
by both old and new name
 Use on-line sources
 Native Plants at CSUDH
http://www.zarachiron.com/2013/06/spanish-men-a-cultural-enigma/
 Scientific name - Scientific name
key
 Common name - Scientific name
key
 USDA Plants database
 Calflora database
© Project SOUND

18. Native Plants at CSUDH http://nativeplantscsudh.blogspot.com/
© Project SOUND

19. Use the ‘pages’ on left of screen
Name to name lists are here
© Project SOUND

20. The PLANTS
database

21. Implications of plant taxonomy/systematics
for the gardener
 Precise, scientific names are
important:
 For scientists – including biomedical
scientists working with plant-based
medicinal chemicals, insecticides, etc.
© 2002 Kristiaan Stuart
Rhamnus ilicifolia
 For you as a gardener – so you
purchase the plant whose
characteristics you want
 Plant systematics provides insights
 Understanding basic characteristics
of groups – requirements,
susceptibilities, toxicities
© Project SOUND

22. Implications of plant
taxonomy/systematics for the gardener
 Conservation – importance
of conserving local
endangered species in
gardens, seed banks, etc.
 Choice of appropriate plant
species – esp. if crosspollination danger [Salvias;
Buckwheats]
 Evolution in the garden
 ‘garden-friendly’ cultivars
(including novel hybrids)
 Selection and climate
change
© Project SOUND

23. Plant anatomy and morphology:
describing plants
© Project SOUND

24. Describing plants: what do those terms mean?
 Stem: bark gray; branches
stiff, generally ascending;
twigs glabrous to finely hairy.

Leaf: evergreen; petiole 2–10
mm; blade 20–40 mm, ovate to
round, thick, glabrous
adaxially, glabrous or hairy,
flat to concave abaxially, base
rounded, tip obtuse, rounded,
or widely notched, margin
entire, irregularly toothed,
or prickly, veins prominent or
not.
http://www.calflora.net/bloomingplants/hollyleafredberry.html
© Project SOUND

25. Describing plants: simple leaves
Margin
Blade tip
 Basic anatomy
 Petiole
 Blade
 Stipule
 Veins
Base
 Midrib
 Veins
 Shape terminology




Overall shape
Blade tip
Blade base
Margins
http://www.robinsonlibrary.com/science/botany/anatomy/leafparts.htm
© Project SOUND

26. Simple vs.
compound leaves
 Clues:
 Look for an axillary bud (just
above the midrib)
 Look at old (or recently fallen)
leaves – the petiole separates
cleanly from the branch (due to
an abscission layer)
http://www.robinsonlibrary.com/science/botany/anatomy/leafparts.htm
 Use plant Family traits – [Pea
family (Fabaceae) usually have
compound leaves]
© Project SOUND

27. Describing plants: leaf shapes
http://www.clemson.edu/extfor/publications/bul117/characteristics.htm
toothed
http://www.nbh.psla.umd.edu/guides/appendix2.html
© Project SOUND

28. Describing plants: what do they mean?
 Stem: bark gray; branches
stiff, generally ascending;
twigs glabrous to finely hairy.

http://www.calflora.net/bloomingplants/hollyleafredberry.html
Leaf: evergreen; petiole 2–10
mm; blade 20–40 mm, ovate to
round, thick, glabrous
adaxially, glabrous or hairy,
flat to concave abaxially, base
rounded, tip obtuse, rounded,
or widely notched, margin
entire, irregularly toothed, or
prickly, veins prominent or not.
© Project SOUND

29. Botanical terms/concepts & plant identification
 Some excellent resources written
specifically for the gardener
 These 3 books are very good
© Project SOUND

30. Help with terminology
 We’ve tried to make using
on-line resources easier by
bringing together the best
in one place – ‘Native Plants
at CSUDH’
 Books
 Allaby, M : Oxford Dictionary
of Plant Sciences
 Beentje, H : Kew Plant
Glossary - an illustrated
dictionary of plant terms
 On-line:
 Several good resources – good
for gardeners
© Project SOUND

31. Let ‘Native Plants at
CSUDH’ help
The ‘Pages’ on the left of the screen provide helpful links to the Project
SOUND/Out of the Wilds plant lists(under ‘Plant Lists’), gardening
information sheets & plant photos (under ‘Gallery of Native Plants’)
© Project SOUND

32. Gallery of Native Plants – Native Plants at CSUDH
There alphabetical name lists:
• Scientific name to current sci name
• Common name to scientific name
© Project SOUND

33. Native Plant Gallery – Native Plants at CSUDH
Click ‘Save’ – then choose to download
or save. You’ll be able to click on links
© Project SOUND

34. Help make the
‘Gallery’ even better
Send us your pictures of CA native
plants growing in garden settings
© Project SOUND

35. Native Plants at CSUDH
http://nativeplantscsudh.
blogspot.com/
Just search ‘native plants
at csudh’ with your favorite
browser
© Project SOUND

36. We’re very familiar with the life stages of
animals
http://www.baby-connect.com/
http://fastfoodies.org/movie-food/elderly-people-on-computer/
http://onlinebusiness.volusion.com/articles/seniors-online/
© Project SOUND

37. Plants have similar – but different – life stages
 Fertilization
 Embryogenesis/seed formation
 Seed germination/early growth
 Juvenile growth (vegetative)
 Mature growth (vegetative)
 Flowering/Fruiting/seed
production
 Senescence
 Death
http://ww2.valdosta.edu/~ckbeck/ebook.html

38. Describing plants: what do they mean?
 Inflorescence: 1–6-flowered,
generally glabrous; pedicel 2–4 mm.
 Flower: generally unisexual;
hypanthium ± 2 mm wide; sepals 4;
petals 0.
 Fruit: 2-stoned, 4–8 mm, red.
Mark W. Skinner @ USDA-NRCS PLANTS Database
© 2002 Kristiaan Stuart
http://www.researchlearningcenter.org/bloom/species/Rhamnus_ilicifolia.htm
© Project SOUND

39. Inflorescence: grouping/arrangement of flowers
http://www.flowers-gardens.net/gardens/types-of-inflorescence.html
Wikipedia has a very good coverage of inflorescence terms
© Project SOUND

40. Flowers are leaves specialized for reproduction
 Calyx (whorl of Sepals) –
protect/attract
 Corolla (whorl of Petals) –
attract
 Stamen – male sex parts
 Filament
 Anther – produces pollen
 Pistil – female sex parts
A ‘perfect’ flower – has all the parts
http://scienceblogs.com/pharyngula/2006/11/20/mads-boxes-flower-development/
 Stigma – receives pollen
 Style – channel
 Ovary – contains eggs
which become seeds
© Project SOUND

41. How does the pollen get to the stigma?
 Falls on it
 Physical agents
 Wind
 Water
 Biologic agents (Mother
Nature’s cupids)







Bees
Flies
Butterflies/moths
Other insects
Hummingbirds
Bats
Other animals
© Project SOUND

42. Take-home messages: pollination
 Getting the pollen to the egg isn’t
easy if you’re a plant – and you
usually need a little help
 The lives of plants and their
pollinators are in intimately
intertwined
What are the likely pollinators of
Hollyleaf redberry?
 Plants and animal pollinators have
evolved together (co-evolution).
 Plants usually don’t waste energy on
things they don’t really need – the
color/scent etc. are there for a
reason
© Project SOUND

43. Pollination and
Fertilization
http://www.educationcaribbean.com/resources/encyclopaedia/science/plants.asp

44. What does it take to form a seed?
http://www.bio.miami.edu/dana/226/226F09_4.html
© Project SOUND

45. The unwritten goal of all living things:
reproduce and disperse
That’s how species survive
through time
© Project SOUND

46. Why the need to disperse?
 To decrease
unhealthy
competition (for
light, water,
other resources)
http://ebd10.ebd.csic.es/ebd10/Dispersal_and_gene_flow_files/shapeimage_2.png
 To colonize new areas – which may have better resources or
other advantages
 To increase genetic diversity within the species or population –
novel combinations that may confer an advantage
© Project SOUND

47. Dispersal is relatively easy if you have
legs or can swim
http://www.immortalhumans.com/early-man-had-the-same-life-span-as-neanderthals/
© Project SOUND

48. Seed dispersal: traveling through space
 Dropping to the ground
 Catapulted from the dry seed
capsule (fruit)
 Carried by physical agents
 Floating on the wind
 Carried by water
 Carried by living agents
 Hitchhiking on animal fur, feathers
or feet
 Travelling through a bird or animal
for eventual deposition
http://science.psu.edu/news-and-events/2010-news/Carlo2-2010
© Project SOUND

49. Clues to dispersal: often easy to read
Box Elder – Acer negundo
CA poppy




Size/weight
Flight/hitchhiking appendages
Inside a fleshy fruit
Characteristics of pod/capsule
http://www.arizonensis.org/sonoran/places/cavecreek.html
Jojoba - Simmondsia chinensis
© Project SOUND

50. Others are a little more difficult
 Pea family


Large, heavy seeds
Characteristic pod
 Plant distribution in landscape

http://www.arizonensis.org/sonoran/places/cavecreek.html
Yellow Paloverde – Parkinsonia microphylla

Along seasonal streams
Seeds distributed by water
 Effective for dispersing large,
heavy seeds over wide area
 Ensures that seeds will be
dispersed at a time conducive
to germination
 Ensures that plants grow
where best suited to survive
© Project SOUND

51. Seed distribution implications for gardeners
 Some seeds are born to naturalize:
small seeds [annual wildflowers]; windborn seeds [Milkweeds]
 Plant species with fleshy fruits and
you’ll attract fruit-eating birds &
other dispersal agents
 Remember, some seeds are meant to
be carried in animal fur (clothing,
etc.) [some grasses; cocklebur]
http://dendro.cnre.vt.edu/dendrology/syllabus/fact
sheet.cfm?ID=491
Yellow Paloverde
Parkinsonia microphylla
 Plants with unusual dispersal
mechanisms may require special
treatments to encourage them to
germinate
© Project SOUND

52. A seed is somewhat like a ‘manned’
space capsule
http://millburyschools.sharepointsite.com/elmwood/lhippert/Picture%20Library74/Forms/DispForm.aspx?ID=3&RootFol
der=%2Felmwood%2Flhippert%2FPicture%20Library74%2F1
http://www.gijoecanada.com/index.php?main_page=product_info&cPath=71_76_
90&products_id=404
 A ‘capsule’ with a protective covering
 Containing
 A living organism: so dry that it’s in a state of suspended
animation
 Provisions for the journey & for re-settlement
 Traveling through space & time
© Project SOUND

53. The consequences of seed travel through
time and space
 Must have adequate protection – for
wide range of possible conditions
 Must have adequate provisions
 Must provide everything needed to
keep the ‘living being’ alive until it
reaches it’s final destination
 Must keep the weight/size down
(usually – depends on dispersal)
 Must not open the hatch-door until
it’s reached its destination and
conditions are ‘favorable’
http://www.ehow.com/info_8547249_stages-plant-reproduction.html
© Project SOUND

54. The mighty seed
monocot seed (corn)
http://generalhorticulture.tamu.edu/HORT604/LectureSupplMex07/HORT604Mexico2007.htm



http://www.cmg.colostate.edu/gardennotes/137.html
Seed coat (testa) – protective coat
Cotyledon/Endosperm - food source
Embryo
 Radicle (embryonic root)
 Hypocotyl/epicotyl (embryonic root/shoot)
 Plumule (embryonic shoot/leaves)
© Project SOUND

55. Overview of Embryonic Development
http://www.pnas.org/content/107/18/8063/F1.expansion.html

56. A completely mature, dry seed remains in
a state of suspended animation…
sometimes for a very long time
© Project SOUND

57. Seed germination: complex process
Koning, Ross E. 1994. Seeds and Seed Germination. Plant Physiology Information Website.
http://carlsbadcommunitygardens.org/2013/04/2nd-annual-carlsbad-seed-swap-at-the-smerdu-community-garden/
 What we’re interested in today is how does a seed begin
the germination process – and what does it need to survive
as a seedling
© Project SOUND

58. You may have noticed that fresh seeds
often germinate more easily
http://viviparouscapsicumfruitescens.blogspot.com/
…but most seeds don’t
germinate prematurely. Why?
© Project SOUND

59. The timing of germination is critical
 Must be adequate resources
for the seedling to survive:
Immediate
future




Water
Light
Nutrients
Possibly other
 Must not have future
conditions that will kill a young
seedling (seedling stage is the
most vulnerable life stage):
Slightly
longer range
California poppy - Eschscholzia californica
 Too low or too high
temperatures
 Drought
 Fire
© Project SOUND

60. Plants have developed several strategies
to prevent premature germination
 Seed quiescence : delay
germination because the external
environmental conditions are not
right : too dry or warm or cold for
germination [most annuals; many
fresh woody plant/perennial seeds]
 Seed dormancy : seed is unable to
germinate in a specified period of
time under environmental
conditions that are normally
suitable for the germination of the
non-dormant seed [many woody
plant species normally facing
challenging conditions]
© Project SOUND

61. Several different processes: separate but
often interrelated
 Seed germination:
 Depends on both external (environment) and internal (embryonic)
conditions [seed maturity]
 Environmental: water, oxygen, + temperature, light
 Seed quiescence:
 Depends on factors in the seed itself – ‘suspended animation’
 Released when proper conditions for germination are present
 Seed dormancy:
 Depends on factors within the seed itself (but may require
environmental cues that promote it)
 Released by exposure to proper environmental conditions (the
‘triggers’) which ‘break’ dormancy and allow germination
 Germination will not occur unless dormancy is broken
© Project SOUND

62. Quiescence: a temporary hold on germination
 Often due to seed dehydration
ZZZzzzzzz
 Seeds in state of ‘suspended
animation’ ; ready to germinate
once environmental conditions
change for the better




http://unrealnature.wordpress.com/2008/10/27/some-assembly-required/
The seed reaches soil
The first rain
The temperature warms up
Etc.
 The risks associated with
quiescence strategy: premature
germination if conditions again
change for the worse [hot, dry
conditions after the first rain]
© Project SOUND

63. Dormancy: longer term strategy
 Is a characteristic of the seed itself (not the environment);
some seeds [those from tropical regions; typical garden plant
seeds] exhibit no dormancy
 Some CA native seeds are dormant when they leave the plant
(primary dormancy) – insures dispersion will occur prior to
germination
 Others only become dormant only when they experience
unfavorable conditions (too dry; too hot or cold) – secondary
dormancy
 Difference between fresh seeds and ‘older’ seeds is usually
explained by secondary dormancy
 Dormant seeds will not germinate unless dormancy is ‘broken’
© Project SOUND

64. Germination and dormancy are two
different processes
http://www.rtbg.tas.gov.au/index.aspx?base=332
© Project SOUND

65. The life cycle of seeds: mediterranean climates
© Project SOUND
http://www.rtbg.tas.gov.au/index.aspx?base=299

66. Why is seed dormancy important?

Ensures time for seed dispersal

Prevents germination during unsuitable ecological
conditions

Enables seeds to survive short periods of favorable
conditions; when germination stimulating factors are
present, but prevailing conditions are not suitable for
subsequent seedling growth and plant development.

Prevents germination of all the seeds at the same time.
The staggering of germination safeguards some seeds
and seedlings from suffering damage or death from
short periods of bad weather, transient herbivores, etc
In other words, the dormancy evolved as a mechanism to
postpone germination until a time and place that not only
supports germination, but also maximizes seedling
establishment and growth.
© Project SOUND

67. Seed dormancy: many variations
 Seed coat-imposed dormancy [AKA Exogenous/External
dormancy] - caused by an impermeable seed coat
 Embryo-imposed dormancy [AKA Physiological/endogenous/
internal dormancy] – caused by the embryo itself; prevents
embryo growth and seed germination until chemical changes
occur within the embryo
 not due to any influence of the seed coat or other surrounding
tissues
 most abundant form of seed dormancy in angiosperm
 thought to be due to the presence of inhibitors, especially ABA, as
well as the absence of growth promoters, such as GA (gibberellic
acid).
 Combinations – why it’s sometimes hard to determine the
factors needed to ‘break dormancy’ in a given species
© Project SOUND

68. Seed coat-induced dormancy: several
common mechanisms
 Seed coat prevents water or
oxygen uptake: [waxy coatings;
special layers in seed coat that
block water]
 Hard seed coat prevents embryo
from growing/emerging [coat must
be softened/broken by exposure to
stomach acids; mechanical means]
 Seed coat contains growth
inhibitors [must be leached away
be repeated rinsing; exposure to
chemicals that break down the
inhibitors]
© Project SOUND

69. Seed coat-induced dormancy: breeching
the seed coat
 Seed coat must be broken down to allow
entry – embryos will germinate readily in the
presence of water and oxygen once the seed
coat and other surrounding tissues are either
removed or damaged.
http://www.seedsplants.kimeracorporation.co
m/articles/19-come-seminare-.html
 Is usually all or none: once seed coat is
breeched there’s no turning back – so timing
is critical
 Typically found in species from the families
Fabaceae, Malvaceae, Chenopodiaceae, and
Liliciae
© Project SOUND

70. Scarification: breaking/fracturing seed
coat to facilitate water/gas uptake
 Mechanical : tumbling, abrasion,
‘nicking’, pounding etc.
 Chemical : usually involves acid
treatment like concentrated H2S04
(sulfuric acid), other acid treatments
http://www.organicgardening.com/learn-and-grow/pretreatments-slowgerminate-seeds
 Physical : hot water treatment; other
heat treatment (burning)
 Soaking/leaching : some seeds
http://mpgranch.com/staff-blogs/tales-of-atransplant/scarification-and-stratification.aspx
© Project SOUND

71. Treatments to break embryo-induced
dormancy vary by plant
 Common requirements/
treatments
 Drying [after-ripening]
 Low temperatures [stratification]
 Alternating soaking/drying
Hollyleaf redberry grows
in dry places, often with
colder winters – may
require stratification
 Applied by mother nature – or by
the propagator
 Clues from the native
environment of the plant
© Project SOUND

72. Chilling (stratification): exposure to coldmoist conditions
 Prevents temperate climate seeds
from germinating until the spring
 Temperatures: 0-10° C (32-50° F)
 Time: usually 1-3 months; seed
supplier may specify
Garden collected seed – may
want to wash first in mild (5%)
bleach solution to prevent fungal
contamination
 Seeds need to be fully hydrated –
stratify in moistened vermiculite
or moist paper towel/coffee
filters in refrigerator
 Need access to oxygen (air)
© Project SOUND

73. Some environmental conditions that break
embryo-induced dormancy in CA native plants










Drying [after-ripening - grasses]
Low temperatures [stratification]
High temperatures [heat stratification]
Light (or dark) exposure
Fluctuating temperatures (repeated heating and cooling over
many months-years),
Fire/smoke chemicals
Freezing/thawing (may require cycles)
Passage through the digestive tracts of animals/birds
Removal/breakdown of fleshy fruit
Acid treatment
© Project SOUND

74. Important points about CA native seeds
 They differ in the amount of stored food
 Small amounts - must start producing quickly
 Large amounts – live off stored ‘food’ for a while
 They differ in the composition of their seed
coat –some are harder than others
 They germinate in response to cues (all seeds)




Water – cue + softens coat (all plants)
Oxygen
Light (small seeds)
+Temperature
 Some seeds are actually dormant until
‘awakened’ by environmental exposures
© Project SOUND

75. Implications for gardeners: seeds
 Storage:
 Store seeds cool and dry
 In general, smaller seeds have
shorter ‘shelf-life’ than larger
seeds
 Planting:
http://www.sierraclubgreenhome.com/go-green/landscaping-and-outdoors/organic-seeds/
Once seeds have germinated,
be sure to keep them adequately
watered – very vulnerable to
dehydration
 Know if your seeds need pretreatment to break dormancy
 Seed company instructions
 On-line
 Inference: place of origin;
taxonomic
 Plant seeds at the correct
depth – some need light to
break dormancy
© Project SOUND

76. Be patient: just because you don’t see
anything, doesn’t mean nothing is
happening
 Root development may occur
before shoot development –
particularly in large seeds
[acorn]
 Dormancy due to germination
inhibitors may take some time
http://www.roguehydro.com/germinating-your-seeds/
 Cycles of hot and cool
 Cycles of wet and dry
 Many ‘washings’ to leach away
or chemically modify the
inhibitors
© Project SOUND

77. How do plants grow? By adding modules
 All plants are based on same
basic pattern:
 Shoot system
 Main stem
 Laterals (branches)
 Root system
 Primary root
 Lateral roots
http://leavingbio.net/flowering%20plants.htm
http://en.wikipedia.org/wiki/Plant_stem Project SOUND
©

78. Shoot and root elongation and development
is segmental in plants
 Phytomere: developmental
segment for shoot (shoot
module) or root (root module)
 Phytomeres develop from
unspecialized cells in special
areas of the plant – the apical
meristems

79. Plant meristems: the plant’s ‘fountain of youth’
 Apical meristems (shoot and
root)
 At the shoot and root tips
 Give rise to the shoot or
root modules
 Result in elongation
 Axial meristems
 Located at/near a node
 Give rise to branches
 Lateral meristems
 Located internally in
shoots/branches
 Responsible for growth in
girth
http://vannocke.hrt.msu.edu/plb865/31oct/meristems.html
© Project SOUND

80. What do the meristems look like?
http://mrzacbio.blogspot.com/
 Central area with lots of simple cells
 Surrounded by area of smaller cells
(due to cell division)
http://www.sbs.utexas.edu/mauseth/weblab/webchap6apmer/6.1-1.htm
 Cells are more specialized looking
(and larger) the further away from
the meristem they are
© Project SOUND

81. All cells, tissues & organs arise form cells
in the apical meristems
 Can traced origins back to
the meristems
 “Fate maps” can be drawn to
trace the evolution of
developing tissues
 Apical meristem contains
 Concentric rings of cells
 Outer-most rings
(segments) form lowest sets
of leaves/stem segments
 Pattern of development is
somewhat like the water
coming out of a fountain

82. Phyllotaxy – the arrangement of
leaves on the stem
http://everydayfibonacci.tumblr.com/
http://www.biologie.uni-hamburg.de/b-online/virtualplants/ipi_ic2.html
 Is genetically determined – that’s
why it’s often used in taxonomy &
plant keys
 Is determined by how much each new
segment is offset around the stem
http://www.ecotree.net/fall_2011.shtml
© Project SOUND

83. Leaf arrangement/position (in relation to
others) – phyllotaxy
©2009 Robert Steers
© 2002 Kristiaan Stuart
© Project SOUND

84. Why do plants grow (at least in part) by
adding new segments?
 Because that’s how they evolved
 Efficiency: particularly in an everchanging environment
 Redundancy/backup : plants need to
be able to regenerate lost parts
 As a consequence of a need for rigid
structure
http://www.calflora.net/bloomingplants/hollyleafredberry.html
© Project SOUND

85. Plant cells are a little different from our cells
 One of the big differences is
that they form cell walls
 Primary cell wall
http://acseenotes.wordpress.com/2011/03/07/cytology/
 Formed first – just inside the
cell (plasma) membrane
 Strong but flexible
 Allows for growth in certain
directions (for example, cells can
elongate)
 Secondary cell wall
 Formed inside the primary cell
wall
 Very strong; inflexible
 No growth after secondary cell
wall is formed
© Project SOUND

86. What the heck! Why would plants do that?
http://montessoriworkjobs.blogspot.com/2011/10/human-skeleton.html
http://www.doitpoms.ac.uk/tlplib/wood/structure_wood_pt2.php
 Strong cell walls give plants the structure needed to grow tall
 But plants still need to keep growing
 Solution: add new segments on top of the old – requires apical
© Project SOUND
meristems

87. Consequences of sedentary life: scary!
 Plants need to keep ‘rejuvenating’
themselves throughout life –
roots and shoots
 Therefore they continue to grow
throughout their lives –
sometimes for 1000+ years
 In order to grow they need
functional meristems [plant stem
cells]
 But what happens when
something happens to an apical
meristem (disease; herbivory)?
Ancient (senescent) Bristlecone pine
© Project SOUND

88. Fortunately, plants have a backup system
 In most plants – most of the time
– segments are added by the
apical meristems
 But there are ‘backup meristems’ –
the axial meristems
 Development of axial meristems is
limited to a degree by the
functional apical meristem –
produces an inhibitory hormone
 Once the apical meristem is gone,
the axial meristems take over the
job of elongation
http://vannocke.hrt.msu.edu/plb865/31oct/meristems.html
© Project SOUND

89. The shapes of plants
http://www.unc.edu/~hallman/cookbook/pumpkin-vine.jpg
http://www.wildmanstevebrill.com/JPEG'S/Plant%20Image
s/Chicory.Rosette.jpg
Stem elongation and control of the number of main shoots
http://www.houstonrose.org/ghbush.jpg
http://www.co.columbia.wi.us/dept/lwcd/images/tree.gif

90. The length of the internode is one
determinant of plant shape
http://www.doyletics.com/digest51.shtml
 The main difference between the shape of a cabbage and a
Southern honeysuckle vine is the length of the internodes
© Project SOUND

91. The length of the internode: genetics and
environment
Southern honeysuckle - Lonicera subspicata
©2009 Robert Steers
Turkish rugging - Chorizanthe stacticoides
© Project SOUND

92. Take home messages
 The basic structure (growth
pattern/shape; mature size) is
genetically determined.
Choose plants accordingly
 But…plants have enough
flexibility programmed in to
allow them to modify their
shape based on conditions:
 Limited water/nutrients –
shorter internodes
 Limited light – longer
internodes as plant ‘reaches
for the sun’
© Project SOUND

93. But internode length doesn’t explain all of
the shape variability
Torrey pine - Pinus torreyana
Lemonadeberry – Rhus integrifolia
© Project SOUND

94. Apical dominance:
not all or none
 Several plant hormones
involved – degree of apical
dominance depends on balance
of these
http://plantphys.info/apical/apical.html
 Degree of apical dominance is
genetically determined – that’s
why a pine tree has a strong
central leader and a shrub has
many equal ‘stems’
 You can (sometimes) make a
strongly dominant form more
shrub-like; it’s more difficult
to go the other way around
http://www.tutorvista.com/content/biology/biology-iv/plant-growth-movements/growthregulators.php
© Project SOUND

95. Tip-pruning (‘pinching’) removes apical
dominance creating a ‘bushier’ plant
http://www.studyblue.com/notes/note/n/botany-exam-3/deck/1607515
 Just remove the tip – don’t need to take much
 Must be done during periods of active growth
 Must do repeatedly for best effects – new side branches
will also exhibit apical dominance
© Project SOUND

96. How far back can I safely tip prune/ prune to
head back?
 Lateral buds have an age – oldest
at the base of a stem/trunk and
youngest at the top
 How long do lateral buds retain the
ability to grow? Alas, no one
answer.
 But there are some rules of thumb:
 Generally - but not always – lateral
buds in older woody parts of stems
have decreased/no growth
potential
 Generally – but not always – buds in
semi-soft or soft wood (younger
parts of stem) will grow
© Project SOUND

97. Take home messages: pruning/shaping
 When shaping woody plants, start
when plants are young
 Know taxa that require careful
pruning:




Ceanothus spp
Arctostaphylos spp
Salvia spp
Pinus spp
 Prune ‘difficult’ species either:
 During growth period (when wood
is still semi-soft) for tip-pruning
 When you can clearly apply the
‘leave 3-4 leafing buds’ rule
© Project SOUND

98. What ‘materials’ do plants need from their
environment?
 Sunlight
 Photons of light (energy for
photosynthesis)
 Air
 Oxygen (to break down stored
food)
 Carbon dioxide (CO2) (for
photosynthesis)
http://www.nelsonthornes.com/secondary/science/scinet/scinet/plants/nutri/c
ontent.htm
How do these move around the plant?
 Soil/medium
 Water
 Nutrients (minerals/
fertilizer)
© Project SOUND

99. Roots (root hairs) are where water and
minerals enter the plant
 Good soils contain what
plants need:
 Water
 Mineral nutrients
(dissolved in the soil water)
 Oxygen (needed by the
roots so that they can
obtain energy & perform
their functions)
http://www.aaronthomaslandscapes.com/blog.html
© Project SOUND

100. The importance of soil water/oxygen balance
http://www.stevenswater.com/articles/irrigationscheduling.aspx
 Too much water
 Root oxygen depleted – decreased uptake of water, minerals
 Too little water
 Roots cannot uptake water or dissolved minerals
That’s why the symptoms or over- and under-watering are the same
© Project SOUND

101. Root characteristics: especially important
with CA native plants
 Coastal sage scrub shrubs
 Primarily fibrous roots
 Primarily shallow roots (< 3 ft)
 Root:shoot ratio increases with
water & nutrient stress
 Chaparral shrubs
http://www.rmrs.nau.edu/watersheds/highlands/vegetation/chaparral/chpla
ntwater.html
Individual species have
characteristic root growth patterns
 Combination of deep and
shallower roots
 Root growth in spring/ summer
 Root:shoot ratio increases with
water & nutrient stress
© Project SOUND

102. Root characteristics of some common CA
native shrubs
© Project SOUND

103. Use root characteristics to choose the
proper plant – and treat it well!
 Taproot
 Likely very drought-tolerant
 Plant is out young – don’t move
 Not for containers
 Fibrous roots
 Look for depth characteristics
 Shallow
 may need occasional or regular
water
 Take care when digging
 Good for containers
 Good choice for slopes, banks
 Lignotuber
http://nativeplants.msu.edu/getting_started/how_to_plant/establishment_
of_rooted_plant_material
 Fire-adapted; may require occasional
rejuvenation
© Project SOUND

104. We’ll discuss roots more next month
© Project SOUND

105. Development of the
vascular system
http://cnx.org/content/m43140/latest/
http://cnx.org/content/m47400/latest/?collection=col11569/latest
 New segments of vascular system are added by apical meristems
 New layers of vascular tissue in older segments are added by
lateral meristems (called vascular cambium)

106. Location of
vascular tissues
 Benefits
http://sci.waikato.ac.nz/farm/content/plantstructure.html
 Two systems in close
physical proximity – key to
water/nutrient movement
 Easy access for loading &
unloading throughout the
plant
 New tissue can be added –
even in woody parts
 Somewhat protected
(fiber cap; bark)
 Drawbacks
 Vulnerable location
http://www2.puc.edu/Faculty/Gilbert_Muth/phot0010.jpg
© Project SOUND

107. Take-home messages: plant vascular system
 Soil water status is important not only
for plant water needs, but also for
mineral nutrition – more next month
 Plant vascular tissues move all sorts of
vital things around the plant body – an
intact system is a must
http://caseytrees.org/blog/summer-tree-care-making-gardening-and-lawncare-safe-for-trees/
 Vascular tissues are vulnerable:
 Girdling
 ‘sucking’ insects [aphids]
 Transport of toxins
https://extension.umd.edu/learn/homeowner-landscape-series-commoncultural-and-environmental-problems-landscapes-hg201
http://cnx.org/content/m47400/latest/?collection=col11569/latest
© Project SOUND

108. We hope you look at plants differently
© Project SOUND

109.  Read a botany book
 Use on-line resources – and refer others to them
 Come back next month when we consider the effects of
climate change
© Project SOUND