12 WINDOW AND PARLOR GARDENING 
woody or fleshy. Fleshy roots, as the root of the common 
Dahlia, serve to store up plant-food for future use, and plants 
so provided for are generally natives of dry and arid regions. 
Aérial roots are found in many Orchids, Ferns, and plants of 
the Pine-apple family. These are usually fleshy and seldom 
branched ; they absorb nutriment from the moisture-laden 
atmosphere. Roots of pot-plants, if over-fed or over-watered, 
are apt to sicken and decay; hence a thorough drainage and 
judicious watering are absolutely necessary to keep such plants 
healthy and vigorous. 
The stem is herbaceous, as in most of our summer-flowers, 
or woody, as in trees and shrubs. ‘The woody stem grows year 
after year, increasing in girth by means of yearly deposits of 
wood below the bark. The herbaceous stem is annual, pro- 
ceeding from a seed or from a perennial root or an under- 
ground stem. The rhizome is a creeping stem generally 
growing below the ground. Rhizomes are often mistaken for 
roots, but the difference lies in the fact that roots produce no | 
buds. All underground parts of a plant producing buds and 
shoots are therefore stems. The Lily of the Valley, the 
Waterflag, and many other familiar plants have fleshy root-like 
stems. Corms and tubers are short, fleshy stems, not unlike 
bulbs in appearance and serving the same purpose, but differ 
by not being composed of scales and layers as are all bulbs. 
Gladiolus and Crocus are common examples. In Cactus and 
other succulent plants, the stem becomes very thick and fleshy, 
and is generally leafless. The green epidermis of such stems 
serves the same purpose as foliage of other plants. 
The stem sometimes becomes long and slender, winding round 
different objects for support, or climbing by means of tendrils. 
Such plants are called vines, creepers, or twining-plants. 
