10 A FLORA OP MANILA 



Cassytha, Loranthaceae, etc. Certain plants that grow on decaying organic 

 , matter and have no green tissue are called saprophytes. 



Plants that live but a short time, a few weeks or months, and die 

 after producing flowers and seeds are called annual, like many herbs; 

 those that live for two years, producing flowers and seeds the second year 

 and then dying, are called biennial, but these, although common in tem- 

 perate countries, are rare in the tropics; those that live from year to 

 year, like all trees and shrubs and many herbaceous plants with under- 

 ground stems, are called perennial. 



THE STEM. — The stem is the axis of the plant, to which are attached 

 all other parts. In most plants the stems are very evident, but in some 

 species they are entirely underground. Plants that show no obvious 

 stem above ground, but bear only leaves and flower-stalks, are called 

 stemless or acaulescent. . 



Stems above ground may be simple or branched. They are usually 

 composed of nodes, the place on the stem or its branches where one or 

 more leaves or branches are borne, and intemodes, the spaces between 

 the nodes. 



Special kinds of stems .or branches have received distinctive names, 

 such as culm, the l^ollow or solid stems of the grasses with well-defined 

 nodes and internodes; sucker, a branch arising from the stem or from 

 roots underground or from adventitious buds on ' the trunk or larger 

 branches of "shrubs or trees, the latter being called stem-suckers; and- 

 stolon, a branch from above ground that becomes prostrate and strikes 

 root at the tip or podes, producing new plants. 



As to differences in texture, stems are classified as herbaceous when 

 living for a short period, forming no permanent woody tissue, and dying 

 after flowering; suffrutescent when more or less woody or half -woody, at 

 least at the base; and woody when forming permanent woody tissue 

 lasting from year to year as in all shrubs and trees. 



As to direction, stems are erect when they ascend perpendicularly 

 from the base; ascending when rising obliquely; decumbent when nxpre 

 or less reclining on the ground at or near the base; prostrate when lying 

 flat on the ground; creeping when closely ■.■p^ressed to the ground and 

 rooting at the nodes; climbing or scandent when ascending by means of 

 the support offered by other plants or .objects, whether by tendrils, 

 special spirally twisted organs, by rooi,Vsi;Si, or by other means. Vines 

 that climb by coiling about other stems or objects are called twining. 



Underground stems assume various Sorm^ and are frequently con- 

 founded with roots. There are four principal kinds, the rhizome or 

 rootstock, the tuber, the rnrw. and the ii/Jh. The rhizome or rootstock 

 is a more or less modified creeping stem growing beneath the surface 

 of the soil; the simpler forms are slender and consist of nodes and 

 internodes bearing scales, as in the mint (ycrba btiena), various perennial 

 grasses, etc., but other forms are thick and fleshy, as in the ginger (luya). 

 A tuber is a stout, thickened portion of a rootstock, bearing buds (eyes) 

 on the sides, as in the potato, but intergrades occur between this and the 

 preceding. A corvi is a short, thick, fleshy, underground stem, usually 

 sending off numerous roots from the lower part, and leaves and flowers- 

 stalks from the upper, as in the taro (gabl). A bulb consists of a small 

 basal solid part, its bulk being made up of thickened scales; those in which 

 the scales clpsely enwrap each other are called tunicated bulbs, as in the 



