ADVERTISEMENTS:
The below mentioned article provides study notes on Taxodium.
Taxodium is not found wild in India. T. mucronatum trees are growing at Forest Research Institute, Dehradun.
The tree is large, evergreen or semi-evergreen and bears two types of branches:
ADVERTISEMENTS:
(i) Persistent branches and
(ii) Deciduous branches.
The persistent branches bear axillary buds while deciduous branches are without axillary buds. The leaves are short, soft, narrow, pointed, and either spirally arranged (as on persistent shoots) or arranged in two-ranks (as on deciduous shoots). The main trunk tapers from base to the top of the tree.
Plants growing in swamps or marshy regions (as in Mexico, Florida) develop vertically growing pneumatophores-like outgrowths (called Cypress Knees) from the roots. They function like pneumatophores or breathing roots of mangrove plants.
Taxodium plants are monoecious and generally bear male and female branches on different branches. Both the cones develop in the axil of scaly leaves near the tips of the branches. Female cones develop irregularly on the shoots in groups of 2-10. Mature male cones are oblong in shape and bear 10-15 stalked microsporophyll’s on the cone axis.
Microsporophyll’s have a broad base and all remain surrounded by ovate scales. Two rows of 8-9 microsporangia are arranged at the proximal end on the abaxial side of microsporophyll. Stomata are present on the lower surface of microsporophyll while its distal portion bears resin ducts. Female cone is round when young but becomes ovoid in later stages.
Each female cone is made of several spirally arranged overlapping bracts. Lower and upper bracts are sterile (i.e. without any ovules) while middle bracts are fertile (i.e. bear ovules). At the base of each pair of ovule is present an ovuliferous scale in a mature female cone.
Each megasporophyll bears 2 or 3 ovules on its abaxial side. As many as ten fertile megasporophylls are present in a female cone. The fully mature female cones are brown and woody structures. The seeds are dark brown, compressed, three-angled and three- winged.
