STRUCTURE OF PLANTS. 
Perennials are those that live and bloom year after year, except under extraordinary 
vicissitudes, many of them blooming the first summer if sown early in the spring. Such 
plants can be propagated by a division of the roots and cuttings as-well as by seeds. Some 
of these cannot be surpassed for utility and beauty, and are best for permanent beds where 
circumstances will not permit the steady attention demanded by other classes of flowers. 
STHMS. 
from the root, and serves to support the leaves, buds and Awers 
It usually seeks the light, appearing above the ground, and is sub- 
divided as follows: S%mfle, when found without branches (8), as 
in the Parnassia; compound, when branched, as in the Chickweed 
(9); forked, when parted into two equal or nearly equal branches, as 
in the Bouvardia (10); erect, when growing upright, ascending, when rising 
obliquely upward— when several stems grow from the same root, the central 
one is often erect and the others ascending, as in the Violet (11); prostrate, 
or procumbent, when it lies flat along the ground, as in the Petunia; creeping, 
or repent, when it runs along the ground and Sénds out roots from its joints— 
sometimes a plant has an upright stem, and sends out creeping shoots from its base, as 
in the Strawberry (12); tw7ning, or voluble, as in the Hop, when they rise by spirally 
coiling themselves around supports; climbing, or scandent, when they rise by clinging 
step by step to other objects, as in the Ivy. 
Stems are classified according to certain peculiarities of size and duration, as follows: 
flerbaceous, when they die down to the ground every year, as in Mint or other herbs, 
whence the epithet; /rztzcose, when living from year to year, and of considerable size, 
like Lilac or other shrubs; sagfruticose, when fruticose or shrubby below, and herbaceous 
above, as the Horseshoe Geranium; suffrutescent, when, the stem has an appearance of 
being moderately shrubby, and is only a little woody, as the Pelargonium; arborescent, 
when approaching to a tree-like appearance, as the Oleander; and arboreous, when it is 
the trunk of a tree properly so called, as the Magnolia. 
The stem is composed —beginning from the center—of the pzth, the soft, spongy 
substance in the center of many plants, consisting of cellular tissue; the wood, or material 
immediately surrounding the pith; the /¢ééer, or inner bark, which is fibrous; the cortex, 
or outer bark, which consists of cellular tissue only; and the epzdermis, or skin—a thin, 
membraneous covering, with pores, that envelops all the rest. The stem, longitudinally 
considered, comprises the zodes, or knots; and zzternodes, or parts between the knots. 
It has been already stated that the stem is usually above ground; there are, however, 
several forms of underground stems, as the rAzzoma, or rootstalk, a creeping stem grow- 
ing wholly or partly beneath the soil; the corm, which is a very short, fleshy rhizoma; 
the 4x6, a shorter stem, usually underground, with excessively crowded and overlapping 
coats; and the dzdblet, which is a small excresence that grows on the older and larger bulb. 
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