the embryo of a germinating seed grows into stem. The epicotyl elongates after embryo growth into the axis (the stem) that bears leaves from its tip, which contain the actively dividing cells of the shoot called apical meristem. Further cell divisions and growth result in the formation of mass of tissue called a leaf primordium. The point from which the Vanda Bryophyllum Cuscuta Tinospora Figure .
: Adventitious Root Modification for Vital Functions hanging root clinging root Photosynthetic root Example: Begonia (Elephant ear plant) and Bryophyllum (Sprout leaf plant). Cauline buds arise directly from the stem either from cut, pruned ends or from branches. Adventitious buds function as propagules which are produced on the stem as tuberous structures. Example: Dioscorea, Agave .
. Bulbils ( or specialized buds) : Bulbils are modified and enlarged bud, meant for propagation. When bulbils detach from parent plant and fall on the ground, they germinate into new plants and serve as a means of vegetative propagation . Example Agave an d Allium proliferum .
. . Types of Stem Majority of angiosperm possess upright, vertically growing erect stem. They may be many types they are (i) Excurrent, (ii) Decurrent, (iii) Caudex and (iv) Culm.
i. Excurrent The main axis shows continuous growth and the lateral branches gradually becoming shorter towards the apex which gives a conical appearance to the trees. Example: Monoon longifolium ( Polyalthia longifolia), Casuarina. ii.
Decurrent The growth of lateral branch is more vigorous than that of main axis. The tree has a rounded or spreading appearance. Example: Mangifera indica. iii.
Caudex It is an unbranched, stout, cylindrical stem, marked with scars of fallen leaves. Example: Cocos nucifera. iv. Culm Erect stems with distinct nodes and usually hollow internodes clasped by leaf sheaths.
Example: Majority of grasses including Bamboo. . . Modification of Stem I.
Aerial modification of stem . Creepers These are plants growing closer (horizontally) to the ground and produce roots at each node. Example: Cynodon dactylon, Centella. .
Photosynthesis – Example: Opuntia, Ruscus, Euphorbia. . Protection – Example: Citrus, Bougainvillea, Acacia. .
Support - Example: