Floral biology of Garlic and Onion Scientific name : Allium sativum Family : Alliaceae Chromosome number : 2n = 2x = 16 Garlic is a herbaceous annual for bulb and a biennial for seed production. Garlic is frost hardy bulbous perennial erect herbs of 30-100 cm in height with narrow flat leaves and bears small white flowers and bulbils. The under-ground stems are modified as bulbs. Scientific name : Allium cepa Family : Alliaceae Chromosome number : 2n = 2x = 16 Habitat & Habit : The onion is a biennial, but can perennate by underground bulbs in favourable conditions. Stem : The true stem of onion is much reduced in size and is hard, erect, short with condensed internodes and flat bottom. It is held underneath the soil. The bulbous structure found above the soil surface known as “pseudostem” is constituted by the accumulation of the tubular leaf sheaths. The short stem produces the slender primary root from the centre of the base. After a definite period, the apex of the stem elongates upward and produces the inflorescence axis or seed stalk known as scape.

2. CLASSIFICATION
Kingdom : Plantae
Division : Angiospermae
Class : Monocotyledons
Subclass : Liliidae
Series : Coronariae
Order : Liliales
Family : Alliaceae
Genus : Allium L.
Species : sativum

3. INTRODUCTION
Scientific name : Allium sativum
Family : Alliaceae
Chromosome number : 2n = 2x = 16
• Garlic is a herbaceous annual for bulb and a biennial
for seed production.
• Garlic is frost hardy bulbous perennial erect herbs of
30-100 cm in height with narrow flat leaves and bears
small white flowers and bulbils.
• The under-ground stems are modified as bulbs.

4. INFLORESCENCE
•At bolting, the plant produces a long, solid and
terete scape or the stalk which terminates into a
cymose umbel enclosed by a beaked spathe,
consisting of flowers and bulbils.
•The scape of garlic is smooth, round and solid
for its entire length unlike Onion, which is
hollow.
•In most of the cultivars the bulbils alone develop
due to abortion of flowers in bud stage.

5. SCAPE AND SPATHE

6. GARLIC BULBIL

7. FLORAL BIOLOGY
Flower : Bracteate, pedicellate, complete, hermaphrodite,
actinomorphic, regular, trimerous, hypogynous, small and white.
Perianth : Perianth six in number, arranged in two whorls of
three each, lobes free, white to purple tinged.
Androecium : Stamens six, inserted within the perianth in two
whorls of three each, anthers exerted.
Gynoecium : Ovary, oblong – ovoid and emarginated at apex,
superior, tricarpellary, trilocular with an exerted style.

8. FLORAL BIOLOGY
Bulbs : The under-ground stems are modified as bulbs. The bulb consists of 6-35 smaller
bulblets called ‘cloves’ and is surrounded by a thin white or pinkish papery sheath.
Fruit : A loculicidal capsule.
Floral Formula : Br, ⊕, , P 3+3, A 3+3, G (3)
Anthesis and Pollination :
•Garlic is highly cross pollinated.
•The tepals and anthers colour turns purple and pink respectively, 6-8 days prior to
anthesis.
•Commonly, under Israeli conditions, anthesis occurs in May. Anthesis of the early and
late flowering genotypes were recorded at the end of April and in mid – June,
respectively.
•6-7 days after anthesis, the stigma receptivity increases concurrently with the anthers
withering.

9. SELFING
Selfing :
Selfing is accompanied by bagging all the umbels of the same plant together and by
shaking or by introducing flies.

10. ONION
Kingdom : Plantae
Division : Angiospermae
Class : Monocotyledon
Sub class : Lilidae
Series : Coronariae
Order : Liliales
Family : Alliaceae
Genus : Allium
Species : cepa

11. INTRODUCTION
Scientific name : Allium cepa
Family : Alliaceae
Chromosome number : 2n = 2x = 16
Habitat & Habit : The onion is a biennial, but can perennate by underground
bulbs in favourable conditions.
Stem : The true stem of onion is much reduced in size and is hard, erect, short
with condensed internodes and flat bottom. It is held underneath the soil. The
bulbous structure found above the soil surface known as “pseudostem” is
constituted by the accumulation of the tubular leaf sheaths. The short stem
produces the slender primary root from the centre of the base.
After a definite period, the apex of the stem elongates upward and produces
the inflorescence axis or seed stalk known as scape.

12. PARTS OF BULBS OF ONION
& GARLIC

13. LEAF
 The aerial leaves are alternate, cylindrical,
long, linear and hollow with parallel venation.
 They are circular in cross section which is a
characteristic feature in Allium cepa.
Each leaf has a broad leaf sheath underneath the
soil, in which the food material is stored.
The leaf sheath is a hollow tube like structure
with an opening at the top.

14. INFLORESCENCE
The inflorescence of onion is a terminal cymose umbel enclosed
by a beaked spathe.
The number of flowers in these smaller inflorescences vary from
five to ten.
The peduncle is long and round, bulged near about the middle and
hollow.
It is also called the scape or flower stalk or the seed stalk.

15. INFLORESCENCE
Spathe enclosing
the umbel
inflorescence

16. FLORAL BIOLOGY
Flower : The flowers are bisexual, actinomorphic, trimerous, hypogynous and
bracteate. Each flower consists of five whorls.
Perianth : Perianth lobes are six in number, free, with imbricate aestivation and
are arranged in two whorls.
Androecium : Stamens are free, six in number arranged in two whorls. The
inner stamens have much broader filaments with dilated bases than the outer
stamens. Anthers are oblong and dithecous.
Gynoecium : The ovary is superior, axile placentation, tricarpellary and
syncarpous, each locule enclosing two ovules. Style is filiform. Stigma minute.
In between the septa, is situated a group of nectary tissue.

17. Fruit : The fruit of onion is a capsule. Each fruit contains six seeds.
Seed : The seeds are albuminous and are small, black, wrinkled and three sided
or fairly semi-circular in shape.
Floral Formula : Br, ⊕, , P 3+3, A 3+3, G (3)
Anthesis and Pollination :
• Onion is a highly cross pollinated crop and shows Protandry.
• The dehiscence of anthers and receptivity of stigma takes place at different
times; this facilitates cross – pollination.
• The dehiscence of anthers and shedding of pollen take place first in the inner
stamens and it is followed in the outer stamens. Anthesis occurs in early
morning (6-7 hrs).
• Over a period of two to three days this process is completed.
Simultaneously, the style starts elongating gradually right from flower opening
but it attains its maximum length only after the anther dehiscence and pollen
shedding in both the whorls of the stamens are over. Only then the stigma attains
its receptivity.

18. SELFING
Selfing :
•Selfing in onion is done only on a limited scale as it becomes difficult to
maintain the inbred lines beyond S2 generation due to drastic inbreeding
depression.
•Selfing is done by putting individual cages over the plants. Flies are generally
used to ensure pollination within cages.
•Sometimes it is convenient to enclose 2-3 umbels of the same plant in a muslin
cloth bag before anthesis.
•After anthesis, the umbels are rubbed against each other daily for a few days to
ensure self-pollination.

19. CROSSING
 It must be understood that cross-pollination through hand
emasculation is extremely difficult.
 Therefore the second choice is a fertile x fertile cross where 2
parental lines are caged together and then pollinated by hand or
with common houseflies, blow flies or bees.
 This method is effective and feasible only when F1 can be
differentiated from both the parental lines in the bulb stage.