Underground stems
From Wikipedia, the free encyclopedia
Under Ground stems are modified plant structures that derive from stem tissue but exist under the soil surface. Plants have two axis of growth, which can be best seen from seed germination and growth. Seedlings develop two structures or axis of growth, one that develops up word out of the soil, called stems, and structures that develop downward which are called roots. The roots are modified to have root hairs and branch indiscriminently with cells that take in water and nutrients, while the stems are modified to move water and nutrients to and from the leaves and flowers. Stems have nodes with buds where leaves and flowers arise at specific locations, while roots do not.
Different forms of underground stems include:
Bulb - Short, upright organ used by plants for food storage or reproduction, with specialized leaves modified into thick flesh scales. Tulips and Lilies.
Corm - Short, upright, hard or fleshy stems covered with thin, dry papery leaves.
Rhizome - With reduced scale like leaves. The top can generate leafy stems while the bottom can produce roots. Iris.
Stolon - Horizontal stems that run at or just below the soil surface with nodes that root. Also called runners.
Tuber - An enlarged fleshy end of a stem, generally from Rhizomes but often also referring to thickened roots too. Irish Potato.
