Diversity of flowering plants

1. Diversity of flowering plants

2. Introduction
• Flowering plants are plants that bear flowers and fruits and form the clade
Angiospermae commonly called angiosperms.
• They include all forbs (flowering plants without a woody stem), grasses and grass-like
plants, a vast majority of broad-leaved trees, shrubs and vines, and most aquatic plants.
• The term "angiosperm" is derived from the Greek angeion ('container, vessel') and
sperma ('seed'), meaning that the seeds are enclosed within a fruit.
• They are by far the most diverse group of land plants with 64 orders, 416 families,
approximately 13,000 known genera and 300,000 known species.[7]
• Angiosperms were formerly called Magnoliophyta

3. • Flowering plants are a diverse group of plants that produce
flowers as their reproductive structures.
• They can be classified into eight groups, but most of them belong
to the eudicot, monocot, and magnoliid clades.
• Flowering plants can have unisexual or bisexual flowers, which
contain either male or female organs, or both.
• The diversity of flowering plants allows them to adapt to different
environments and pollinators.

4. Ecological diversity
• The largest angiosperms are Eucalyptus gum
trees of Australia and Shorea faguetiana,
Dipterocarp rainforest trees of Southeast Asia,
both of which can reach almost 100 meters
(330 ft) in height.
• The smallest are Wolffia duckweeds which
rootless float on freshwater, each plant less
than 2 millimeters (0.08 in) across.

5. • Considering their method of obtaining
energy, some 99% of flowering plants are
photosynthetic autotrophs, deriving their
energy from sunlight and using it to
create molecules such as sugars.
• The remainder are parasitic, whether on
fungi like the orchids for part or all of
their life cycle, or other plants, either
wholly like the broomrapes, Orobanche,
or partially like the witchweeds, Striga.
Gunnera captures sunlight for
photosynthesis over the large surfaces
of its leaves, which are supported by
strong veins.
Orobanche purpurea, a
parasitic broomrape with no
leaves, obtains all its food
from other plants.

6. • In terms of their environment, flowering plants are cosmopolitan, occupying a wide
range of habitats on land, in fresh water and in the sea.
• On land, they are the dominant plant group in every habitat except for frigid moss-
lichen tundra and coniferous forest.
• The seagrasses in the Alismatales grow in marine environments, spreading with
rhizomes that grow through the mud in sheltered coastal waters.

7. • Some specialized angiosperms can flourish in extremely acidic or alkaline habitats.
• The sundews, many of which live in nutrient-poor acid bogs, are carnivorous
plants, able to derive nutrients such as nitrate from the bodies of trapped insects.
• Other flowers such as Gentiana verna, the spring gentian, are adapted to the
alkaline conditions found on calcium-rich chalk and limestone, which give rise to
often dry topographies such as limestone pavement

8. • As for their growth habit, the flowering plants range from small, soft herbaceous
plants, often living as annuals or biennials that set seed and die after one growing
season, to large perennial woody trees that may live for many centuries and grow
to many meters in height.
• Some species grow tall without being self-supporting like trees by climbing on
other plants in the manner of vines or lianas.

9. Taxonomic diversity
• The number of species of flowering plants is estimated to be in the range of
250,000 to 400,000.
• This compares to around 12,000 species of moss[29] and 11,000 species of
pteridophytes.
• The APG system seeks to determine the number of families, mostly by molecular
phylogenetics.
• In the 2009 APG III there were 415 families. The 2016 APG IV added five new
orders (Boraginales, Dilleniales, Icacinales, Metteniusales and Vahliales), along
with some new families, for a total of 64 angiosperm orders and 416 families.

10. • The diversity of flowering plants is not evenly
distributed. Nearly all species belong to the eudicot
(75%), monocot (23%), and magnoliid (2%) clades.
• The remaining five clades contain a little over 250
species in total; i.e. less than 0.1% of flowering plant
diversity, divided among nine families.
• India there are about 45,000 plant species are known
that represent about 7% of the world’s flora. Nearly,
4900 species of angiosperms are endemic to India.
• The 25 most species-rich of 443 families, containing
over 166,000 species between them in their APG
circumscriptions, are:

11. History of classification
• The botanical term "angiosperm", from Greek words angeíon (ἀγγεῖον 'bottle,
vessel') and spérma (σπέρμα 'seed'), was coined in the form "Angiospermae" by Paul
Hermann in 1690, including only flowering plants whose seeds were enclosed in
capsules.
• The term angiosperm fundamentally changed in meaning in 1827 with Robert
Brown, when angiosperm came to mean a seed plant with enclosed ovules.
• In 1851, with Wilhelm Hofmeister's work on embryo-sacs, Angiosperm came to have
its modern meaning of all the flowering plants including Dicotyledons and
Monocotyledons.

12. • The APG system treats the flowering plants as an unranked clade
without a formal Latin name (angiosperms).
• A formal classification was published alongside the 2009 revision
in which the flowering plants rank as the subclass Magnoliidae.
• From 1998, the Angiosperm Phylogeny Group (APG) has
reclassified the angiosperms, with updates in the APG II system
in 2003, the APG III system in 2009, and the APG IV system in
2016.

13. Phylogeny
• External
• In 2019, a molecular
phylogeny of plants
placed the flowering
plants in their
evolutionary context:

14. • Internal
• The main groups
of living
angiosperms are:

15. Reproduction

16. Major food-providing families

17. Dicotyledons and Monocotyledons
• The dicotyledons, also known as dicots (or, more rarely, dicotyls), are one of the two
groups into which all the flowering plants (angiosperms) were formerly divided.
• The name refers to one of the typical characteristics of the group: namely, that the seed
has two embryonic leaves or cotyledons.
• There are around 200,000 species within this group.
• The other group of flowering plants were called monocotyledons (or monocots), typically
each having one cotyledon.
• Historically, these two groups formed the two divisions of the flowering plants.

18. Comparison between monocotyledons &
dicotyledons

19. Polypetalae vs Gamopetalae
• Polypetalae was defined as including plants
with the petals free from the base or only
slightly connected.
• Members of Polypetalae contain bitegmic
ovules (i.e., ovules having two integuments).
• Gamopetalae: Petals are fused or united

20. Ranales:
RANUNCULACEAE
(THE BUTTERCUP FAMILY)

21. RANUNCULACEAE
(BUTTERCUP FAMILY)
• A cosmopolitan family with larger diversity in the wet temperate regions
extending into the mountains of the tropics;
• 52 genera and 2,500 species of erect, prostrate or acaulescent herbs and
herbaceous to woody vines.
• The family is represented in the Neotropics by 11 genera and 100 species, of
which only 22 are reported as climbers, except Thalictrum podocarpum DC.,

22. • All climbing species in the Neotropics belong to the genus
Clematis; most species occur in moist, middle to high-elevation
humid forests.
• Diagnostics: Vines with compound leaves, in Clematis opposite
with prehensile petioles and/or leaf rachides; flowers with
numerous stamens and apocarpous gynoecium.

23. Common Genera
• The largest genera are
• Ranunculus (600 species),
• Delphinium (365),
• Thalictrum (330),
• Clematis (380), and
• Aconitum (300).
• Paeonia, Aquilegia etc.

24. Aconitum deinorrhizum Stapf
Delphinium Ranunculus
Clematis
Thalictrum

25. A. Diagnostic Characters:
• Herbs, leaves exstipulate, incised blades, sheathing bases,
• Flowers: hypogynous, spiral, or spirocyclic; sepals often deciduous,
• usually petaloid; calyx and corolla free;
• Stamens: indefinite, free;
• Carpels: polycarpellary, apocarpous;
• Fruit: aggregate.

26. B. Vegetative Characters: Habit:
• The plants are annual or perennial herbs or
climbing shrubs (Clematis, Naravelia), rarely
trees.
• They perennate by means of tuberous roots
(Aconitum) or rhizomes.
Clematis
Aconitum

27. Root:
• Tap root, adventitious or
• Tuberous (Ranunculus, Aconitum, Paeonia).
• The tap root system is in the initial stage but is sooner or later replaced by
the adventitious roots.
• Stem:
• Mostly herbaceous, aerial, and annual, in some perennials it is
underground rhizomes (Anemone) and climbing (Clematis).

28. Leaf:
• Generally simple, alternate, or opposite (Clematis)
• exstipulate rarely stipulate (Thalictrum),
• sheathing leaf base, petiolate rarely sessile
(Delphinium).
• In some aquatic species leaves may show
dimorphic (Ranunculus aquatilis);
• unicostate or multicostate reticulate venation.

30. C. Floral Characters:
• Inflorescence:
• Solitary terminal (Anemone),
• Axillary (Clematis),
• Raceme (Aconitum, Delphinium) and
• Cymose (Ranunculus spp.).
• In the species of Nigella, in the beginning, a terminal flower is
formed but later on the raceme develops.

31. Flower:
• Pedicellate, ebracteate rarely bracteate,
hermaphrodite, (unisexual in Thalictrum).
• Mostly actinomorphic (Ranunculus) rarely
zygomorphic (Delphinium and Aconitum)
hypogynous, and sometimes a disc is
found below the gynoecium, e.g., Paeonia.
• complete, pentamerous.
actinomorphic
(Ranunculus

32. Perianth:
• In most of the flowers of this family, the perianth is not distinguished into calyx and
corolla.
• It is simple, petaloid, and variously colored.
• The perianth is often associated with nectar-secreting structures of various forms.
• In Ranunculus, the petals possess pocket-like nectaries at their bases.
• The nectaries are supposed to be the modification of the petals.
• In certain genera, the nectaries develop in the association of sepals, stamens, or
even carpels.

33. Calyx:
• There is no distinction of calyx and corolla in most of the
flowers.
• Sepals 5-8, caducous, polysepalous, petaloid, sometimes spurred
or cucullate.
• Imbricate or valvate aestivation.

34. Corolla:
• The corolla is apopetalous with few–∞
[rarely 0] petals, sometimes spurred.
• Petals 5, or 04 in Clamitis polypetalous,
variously colored, caducous, or wanting;
nectaries present at the base of petals.
• Petals are united to form spur
(Delphinium).
• Caltha, Clematis and Anemone petals are
together and the sepals become petaloid.

35. Androecium:
• Stamens indefinite, polyandrous, spirally
arranged on the thalamus.
• In some genera like Helleborus, Nigella, and
Aquilegia the stamens are arranged in definite
rings.
• The anthers are dithecous, extrose, adnate, and
dehiscing longitudinally.
• The filaments are beautifully colored in
Thalictrum.

36. Gynoecium:
• It consists of indefinite carpels (polycarpellary), the carpels
are free, i.e., apocarpous.
• In Delphinium the number of carpels is reduced to one.
• In Aconitum sp., there are three to five carpels.
• In Nigella, there are 5 to 8 carpels, which are more or less
united (i.e., syncarpous).
• In each ovary the number of ovules ranges from one to many.
The ovules are anatropous.
• The placentation is either marginal (e.g., Delphinium), or
basal (e.g., Ranunculus).

37. Fruit:
• The fruit is usually either an etaerio of achenes, e.g., Ranunculus or
• an etaerio of follicles, e.g., Aconitum.
• In Actaea, it is a berry.
• In Nigella it becomes a capsule, because of the fusion of carpels.
• In some of cases the achenes possess long persistent feathery styles
that help in the distribution of the fruits by means of wind, e.g.,
Clematis and Anemone.

41. Economic Importance of Family –
Ranunculaceae:
• 1. Condiment:
• The seeds of Nigella sativa (H. Kalongi) are used as spice in pickles.
• 2. Medicinal:
• Aconitum hererophyllum and A. napellus yield some alkaloids specially aconitin.
This is used in acute and inflammatory diseases.
• The roots of Thalictrum yields “mamira”, which is used in opthalamia. Anemone
pulsatilla is mostly used in feminine diseases and gastric derangements. Pulsatilla
obtained from Anemone pulsatilla is a good medicine for menstrual disorder.

42. • Cimicifuga racemosa gives the black Snake root containing resins. This
has been recommended for treatment of cholera and nervous pain.
• Helleborus niger and H. foetida produce glycosides useful as
purgatives in veterinary practices. Delphinium staphisagria is used as
antiparasitic ointment.
• 3. Ornamental:
• Some of the plants are cultivated in gardens for their beautiful flowers
viz., Ranunculus, Delphinium, Naravelia, Clematis, Nigella and Caltha.

43. Affinities of Ranunculaceae:
• The family Ranunculaceae is one of the most primitive of the
dicotyledons.
• Hutchinson, Bentham and Hooker have placed the family in the
class of very early dicotyledons.
• Engler, Rendle and others put the family under the
archichlamydeae.

44. The family is in its close relationship with the
monocotyledons due to the a following facts:
• (i) Tubular cotylar sheath formation and union of two cotyledons in Ranunulus ficaria, the sheath
during germination is pierced by epicotyl.
• (ii) Leaf bases are broadened into sheath and rhizome formation.
• (iii) The course of vascular bundles and scattered arrangement in the stem of certain genera, e.g.,
Cimicifuga.
• (iv) The endospermous seed with apical small embryo and copious endosperm.
• (v) Lastly the free carpels, the resemblance of flowers with Alismaceae.
• The family can be linked with Rosaceae on account of free and numerous stamens and carpels.
• The dimorphic leaves and hypogynous followers of Ranunculaceae trace the relationship with the
family Nymphaeaceae.