Types of Stem

Stems fall into three broad growth-habit groups. Most angiosperms have an upright, erect stem, of four kinds: excurrent, where the main axis grows continuously while lateral branches shorten progressively toward the apex, giving a conical crown (Polyalthia longifolia, Casuarina); decurrent, where lateral branches grow more vigorously than the main axis, giving a rounded, spreading crown (Mangifera indica, Azadirachta indica, Tamarindus indicus, Aegle marmelos); caudex, an unbranched, stout, cylindrical stem marked with the scars of fallen leaves (Cocos nucifera, Borassus flabelliformis, Areca catechu); and culm, an erect stem with distinct nodes and usually hollow internodes clasped by leaf sheaths, typical of grasses including bamboo.

Trailers (stragglers) are weak stems that spread over the ground without rooting at the nodes; they are prostrate/procumbent when they lie flat on the ground throughout (Evolvulus alsinoides, Indigofera prostrata), decumbent when they lie flat but turn erect at flowering (Portulaca, Tridax, Lindenbergia), or diffuse when the trailing stem branches widely as it spreads (Boerhaavia diffusa, Merremia tridentata). …