The potato is a tuber that was botanically named Solanum tuberosum in 1596. It develops from underground stolons and stores starches and sugars. Tubers vary widely in size, weight, and color. They have scars from scale leaves, multiple eyes that are axillary buds, lenticels for gas exchange, and an almost impermeable skin for protection. Potatoes are grown for their starchy tubers which are eaten around the world.

1. POTATO
The potato is a tuber—a short, thick, underground stem with stored starches and sugars—of the potato plant. It was given
its botanical name, Solanum tuberosum, in 1596 by the Swiss botanist Gaspard Bauhin
S. tuberosum is an erect, juicy herb with numerous fleshy, robust, angular, branched stems up to 1.2 m tall and
subterranean tubiform stolons. Root system usually 40-50 cm deep, without obstructions up to 1 m. Tubers developing at
the tip of the stolons, globose to ellipsoid, very variable in size, weight and colour; tuber skin with scars of scale leaves
('eyebrows'), axillary buds ('eyes', usually several eye buds per eyebrow), numerous lenticels, almost impermeable to
chemicals, gases and liquids, providing good protection against microorganisms and water loss; number of eyes very
variable, normally about 10-15 on a tuber of 50 g.

2. Inflorescence:
The complete flower, including bud, pedicel and
peduncle
Internode:
The portion of the stem between the nodes or branches
of the stem;
Leafstalk:
The petiole, midrib, central vein, or supporting stalk of
a leaf;
Node:
The slightly enlarged part of a stem where buds are
formed and where leaves, branches and eyes originate;
Petiole:
The stalk connecting a leaf or leaflets to a stem;
Senescence:
To die prematurely as a result of stress from environmental
conditions or disease, or to die as a result of maturity (old age).
Senescence may be a gradual process or sudden occurrence;
Stolon:
The underground stem of a plant, the end of which may form a
tuber;
Tuber:
The short fleshy underground stem bearing buds or eyes;
Variety:
Seed potatoes that:
 are distinguished by common morphological, physiological, cytological, chemical or other common characteristics, and
 retain their distinguishing characteristics when reproduced;
Wings:
Protruding ridges running along the stem.

3. Apical:
Usually refers to terminal leaflets or the eye, bud, or rose end of
tubers
Axil:
The upper angle between a branch or leaf and the stem from
which it grows;
Axillary bud:
Located at the juncture of the stem and leaflet which may give
rise to secondary branches;
Bud:
Sprout or shoot consisting of rudimentary foliage or floral leaves;
Cultivar:
A variety of potatoes;
Eyebrow:
The ridge over the eye of a potato;
Foliage:
Masses of leaves and stems that make up a plant;
Haulm:
Plant stems or stalks; the vines of potato plants;

4. A typical potato leaf is
composed of two to four pairs
of primary leaflets arranged
on the mid-rib with a terminal
leaflet on the end
Leaves
Leaves alternate, petiolate, odd pinnately compound, with or without numerous interstitial leaflets, in outline
10-30 cm x 5-15 cm; lateral leaflets opposite or alternate, usually 3-4 pairs, very unequal in size, largest ones
stalked, ovate to ovate-elliptical, 2-10 cm x 1-6 cm, smallest ones subsessile, ovate to suborbicular, 1-15 mm
in diameter; terminal leaflet usually largest; all leaflets thinly to densely pubescent, dark green, pinnatinerved.

5. Between the primary leaflets are
smaller ones, called secondary
leaflets, which are often placed
irregularly along the mid-rib.
Tiny inconspicuous rudimentary or
tertiary leaflets can also be evident
along the mid-rib. The leaf is
attached to the plant by a petiole.

6. Open Leaf Structure Closed Leaf Structure

7. Depending on the variety, the leaf may:
•be long or short;
•be rigid, drooping or spreading;
•be flat or with side leaflets arched or drooping; or
•have a distinct petiole angle between leaf and stem
which occasionally can be used as a distinguishing
feature.
Arrangement and number of leaflets whether primary,
secondary or rudimentary, can also vary according to
variety. Leaflets may:
•be light, dark or grey-green in color;
•be hairy, smooth or wrinkled;
•be waxy, dull or glossy;
•be large or small;
•be broad or narrow;
•be flat or somewhat folded; or
•have equal or unequal lobes.

8. Stems
Identification criteria for stems include:
•Amount and location of pigment;
•Thickness;
•Hardness;
•Branching or non-branching habit;
•Stem emergence;
•Internode length (between leaves);
•Node size (swollen nodes are typical of a few varieties);
•Wing structure either wavy or straight.
Wings are protruding ridges running along the stem. Their
characteristic of being wavy or straight are often very useful in
confirming variety identification (see Figure 3-4). In most
potato variety descriptions, mention is only made to wing
structure when it is wavy. In all other cases it is straight or
nearly so. Incidentally, most varieties have hollow internodes.
Stems up to 1.5 cm in diameter,
usually hollow, winged; wings
sometimes decurrent and
undulate-crenulate.

9. Potato Stems Showing Types of Wings
Stem A demonstrates a straight, double
wing.
Stem B demonstrates a waved, double
wing.
Finally, Stem C demonstrates a slightly
waved, double wing.
Particularly, stem B has a dentate wing
while stem C is more undulate.

10. Inflorescence
The term inflorescence includes the complete pedicel (stalk which holds individual flowers), bud and peduncle
(stalk that holds flower clusters)
Potato Inflorescence
Potato flowers may be:
•White,
•Purple, and
•Faint blue.

11. Potato Flower Cross Sectional View
Inflorescence a many-flowered cymose panicle, sometimes with small bracteoles; peduncle 5-15 cm
long, branching above; pedicel up to 3.5 cm long, articulate at or above the middle; flowers white or
white suffused with pink or violet, typically with a greenish-yellow central star

12. Tubers
The end of the tuber which joins the stolon is called the stem end; the other end where the eyes are clustered is
known as the bud end
Tuber Shape

13. Lenticels are breathing pores that appear as tiny slits on the
tuber surface. They are the gateway for the gas exchange
(primarily to take in oxygen and exchange carbon dioxide) in
the tuber necessary for growth and development. Potato tubers
have 28 to 274 lenticels per tuber. Lenticel numbers will vary
by cultivar and tuber size. As tubers rapidly grow, the
rupturing of the periderm often forms more lenticels.

14. Fruit a subglobose berry, up to 2 cm
in diameter, yellow-green, 2-
carpellate, many-seeded, poisonous.
Seed flat, subcircular to ovate, 1-3
mm in diameter, pale yellow-
brownish.

16. Sweet Potato/ Ipomoea batatas/ Convolvulaceae/2n = 6X = 90/ Ipomea trifida

17. Arrowroot / Maranta arundinacea/ Marantaceae
Arrowroot is an erect, perennial plant growing
about 1.2 metres tall. It has a shallow root
system, with rhizomes that penetrate more
deeply into the soil.
The plant produces a starch-rich root that is the
main source of arrowroot and also has various
medicinal applications. Often harvested from
the wild, it is also widely cultivated in tropical
regions for its root and is often grown as a
ground cover and ornamental in tropical
gardens and as a pot plant in cooler climates

18. Cassava/ Tapioca/Manihot esculenta/Euphorbiaceae/ 2n=36

19. •Colocasia and Xanthosoma together are known
as coco yam.
•In Colocasia, leaves are peltate and sterile
appendage is at top of spadix.
•In Xanthosoma, leaves are sagitate and sterile
appendage is absent.
Colocasia (Colocasia esculenta L. Scott)/ Araceae

20. Xanthosoma sagittifolium/ 2n = 26/ Araceae
•The genus Xanthosoma belongs to tribe
Colocasia. Tannia is a tall herbaceous
plant growing to 1.5 to 2.7 m and has
about 6 large outspreading hastate leaves
in contrast to peltate leaves in taro.
•In tannia, mother corm is more or less
cylindrical and surrounded by cormels
which develop from lateral buds adjacent
to leaf scars on the corm. Similar to taro,
mother corms and cormels are used
for planting. Since plants grow
vigorously, tannia is widely spaced at 1 x
I m.

21. Amorphophallus (Elephant foot yam)/
Amorphophallus paeoniifolius/ 2n = 28/ Araceae

22. Dioscorea/ Araceae
Greater yam (Dioscorea alata) (Hindi : Ratula) (2n = 20, 30,
40-80)
White yam (D. rotundata)
Lesser Yam Dioscorea esculenta
2n = 40,60,90,100

23. Jerusalem artichoke (Helianthus tuberosus

24. Horseradish (Armoracia rusticana, syn. Cochlearia armoracia)

25. Morphology
Sweet potato is a perennial plant mainly grown as an annual. The roots are adventitious, mostly located within the
top 25 cm of the soil. Some of the roots produce elongated starchy tubers that vary largely in shape, colour and
texture depending on the variety. The flesh of the tubers can be white, yellow, orange and purple whereas their skin
can be red, purple, brown or white. The stems are creeping slender vines, up to 4 m long. The leaves are green or
purplish, cordate, palmately veined, borne on long petioles. Sweet potato flowers are white or pale violet, axillary,
sympetalous, solitary or in cymes. The fruits are round, 1-4 seeded pods containing flattened seeds
Sweet potato

26. Growth habit. The sweet potato is a herbaceous and perennial plant. However, it is grown as an annual
plant by vegetative propagation using either storage roots or stem cuttings. Its growth habit is predominantly
prostrate with a vine system that expands rapidly horizontally on the ground. The types of growth habit of
sweetpotatoes are erect, semierect, spreading, and very spreading

27. Root system. The sweetpotato root system consists of fibrous roots that absorb nutrients and water, and anchor
the plant, and storage roots that are lateral roots, which store photosynthetic products.
The root system in plants obtained by vegetative propagation starts with adventitious roots that develop into
primary fibrous roots, which are branched into lateral roots. As the plant matures, thick pencil roots that have
some lignification are produced. Other roots that have no lignification, are fleshy and thicken a lot, are called
storage roots.
Plants grown from true seed form a typical root with a central axle with lateral branches. Later on, the central
axle functions as a storage root

28. Tuber-root. It is also called
storage root have a skin
coloured from red to purple,
from brown to white
depending on the variety; as
well as the pulp that varies
from white to yellow, orange
or purple.
A tuberous root or storage
root, is a modified lateral root,
enlarged to function as a
storage organ.

29. Stem. A sweetpotato stem is cylindrical and its length, like that of the internodes, depends on the growth habit
of the cultivar and of the availability of water in the soil. The erect cultivars are approximately 1 m long, while
the very spreading ones can reach more than 5 m long
Leaves. The leaves are simple and spirally arranged alternately on the stem in a pattern known as 2/5
phyllotaxis (there are 5 leaves spirally arranged in 2 circles around the stem for any two leaves be located in
the same vertical plane on the stem).

30. The leaf color
can be green-
yellowish, green
or can have
purple
pigmentation in
part or all the
leaf blade. Some
cultivars show
purple young
leaves and green
mature leaves.

31. Flowers. Sweetpotato cultivars
differ in their ability of flower.
Under normal conditions in the
field, some cultivars do not flower,
others produce very few flowers,
and others flower profusely.
The inflorescence is generally a
cyme

32. Fruits and seeds. The fruit is a capsule,
more or less spherical with a terminal tip,
and can be pubescent or glabrous. The
capsule turns brown when mature.

33. Storage-root. The storage roots are the commercial part of the sweetpotato plant, and sometimes are mistakenly
named "tubers". Most cultivars develop storage roots at the nodes of the mother stem cuttings that are
underground. However, the very spreading cultivars produce storage roots at some of the nodes that come into
contact with the soil.
The parts of the storage roots are the proximal end that joins to the stem, through a root stalk, and where many
adventitious buds are found from which the sprouts are originated; a central part which is more expanded; and the
distal end that is opposite to the root stalk.

34. Type of storage-root formation