Annual herbs, undershrubs or perennial shrubs or rarely small trees, all parts
irregularly dotted with black oil-glands. Leaves palmately lobed, sometimes entire,
palminerved, usually with nectaries on the main basal veins beneath. Flowers solitary,
axillary, large, showy; Pedicels not jointed, usually with nectaries below insertion of
epicalyx segments. Epicalyx segments 3, free or connate at base, foliaceous, entire or
dentate to deeply incised. Calyx campanulate, smaller than epicalyx, truncate, undulate
to 5-dentate or 5-lobed, usually with 3 nectaries at base, persistent. Corolla yellow or white, sometimes red or purple with a deep purple centre. Staminal column included,
antheriferous throughout. Ovary 3 -
5-loculed, ovules many in each locule; style 1, short;
stigma clavate, 5-sulcate. Capsules ovoid to globular rarely fusiform, acute or acuminate; 3 -
5-loculed. Seeds ovoid to obovoid, densely covered by unicellular 1 - 6.5 mm
long woolly hairs (lint or floss) and with or without short dense hairs (Fuzz).
Throughout tropics and subtropics of the world, ca 35 species; one in India.
Notes.
India is the earliest country where cotton was first used for making fabrics as
evidenced by the discovery of cotton from excavation at Mahenjodaro, the date of which
is estimated to be 2750 -
3000 B.C.
Cultivated cottons fall under 4 species of Gossypium, viz. G. arboreum, G. herbaceum, G. barbadense and G. hirsutum. Each of these species have a large number of races
based on geographical distribution and associated genetical features. A number of
cotton cultivars belonging to all the above species are cultivated as a commercial crop
in India except G. barbadense which is only to be found as a homeyard plant in many
states. Commercially the cotton belonging to G. herbaceum constitutes a larger percentage of medium staple cotton grown in India. G. stocksii Masters is the only wild species
occurring in India.
b. Seeds with dense long woolly hairs and with fine short tomentum
2
2a. Epicalyx segments entire to serrate
3
b. Epicalyx segments laciniate
4
3a. Epicalyx segments connate at base for 1 cm or more, entire or 3 -
4 -toothed near apex, closely
embracing the flower; capsules ovoid; lobes or segments of leaves linear to lanceolate with an extra tooth in sinuses
b. Epicalyx segments free or connate at the very base for ca 5 mm, 7 -
9-toothed or lobed at apex, flaring
widely from the flower; capsules globose or oblong; lobes or segments of leaves ovate to oblong or elliptic without any extra tooth in sinuses
4a. Leaves palmiparted, segments ovate to oblong; staminal column 3.5 -
4 cm long, with compact stamens
on filaments of equal length; seeds with floss and fuzz only at the hilum.
b. Leaves palmilobed to palmifid, lobes deltoid to ovoid; staminal column 1 -
2 cm long with loosely arranged stamens, filaments longer towards apex; seeds with floss and fuzz all over or only
at the hilum
