<r fry J. 
Principal Species, 
YOUTH AND AGE 275 
SILPHIUM LACINIATUM (torn). Stem rough with 
bristles, 3 to 6 feet high. Radical leaves 1} to 23 feet long, 
lance-shaped in general outline, but cut up into many slender lobed 
segments ; stem-leaves smaller, more simply lobed in a pinnate manner, 
- Flower-heads 1 to 2 inches across, in a loose raceme ; July. 
S. PERFOLIATUM (stem passing through leaves). Cup-plant. Stem 
square, 4 to 8 inches high. Leaves oval, entire, 6 to 15 inches long ; 
upper pairs joined by their bases, thus forming a cup round the stem; 
lower ones on winged footstalks, which expand and unite by their bases. 
Flower-heads arranged in corymbs; J uly. Introduced 1766. 
S. TEREBINTHINACEUM (turpentiny). Prairie Burdock. Stem 
smooth, 4 to 10 feet high, branched near the summit. Leaves rough, 
oval, somewhat heart-shaped, 1 to 2 feet long, on slender stalks. Flower- 
heads small; July to September. Introduced 1765. 
ities From what has been said of the character of these 
plants as weeds on the American prairies, it will be under- 
stood that their cultivation is a simple affair. They are somewhat 
coarse-growing plants and most suitable for the wild-garden or to cover 
unsightly objects in the garden. They thrive in any kind of soil, even 
wet clayey soil agreeing with them. Propagation is most easily effected 
by dividing the clumps. 
LOUTH AND AGB 
Natural Order Composirz. Genus Zinnia 
ZINNIA (named in honour of Professor John G. Zinn of Gottingen, 
(1727-1759). A genus comprising about a dozen species of half-hardy 
annuals or perennials, herbs or sub-shrubs, with entire, opposite leaves, 
and solitary flower-heads. The involucre is more or less bell-shaped 
with several series of bracts: the ray-florets strap-shaped in one series, 
the disk-florets tubular, five-cleft at the mouth. The species are 
restricted to America as a natural habitat, and most of them are peculiar 
to Mexico. 
Zinnias have been known in British gardens since 
the year 1753, when Z. paueciflora was introduced, followed 
_ Seventeen years later by the similar Z. multiflora. Z. elegans, the 
_ most important species, and the only one generally grown, was intro- 
duced a hundred years ago. Cultivation has turned its single series of 
ray-florets into many, so that the disk-florets are few. There are a 
number of garden varieties, as well as some hybrid forms, of which Z 
