Trees, Shrubs and Vines 
calyx, but no corolla; still higher, each has both calyx 
and corolla; next, stamens and pistils are combined in 
the same flower, but without calyx or corolla; then 
with only calyx, and, last and highest of all, the com- 
plete flower contains all four parts, each variously 
elaborated according to the species. 
This is substantially the order of gradation from the 
rudimentary willow up to the gorgeous rhododendron 
and the magnificent yulan. But for our present pur- 
pose it is sufficient to observe that the very manner in 
which the blossoms are clustered on the tree is to a great 
degree indicative of their stage of evolution, the most 
rudimentary of the foregoing types being generally 
crowded in long, slender, pendent tassels, called catkins 
or aments, whereas the more complex types are either in 
large single flowers, as in the tulip-tree or magnolia, or, 
if clustered, never in the form of the slender, crowded 
catkin, but loosely conjoined, as in the apple-tree, 
horse-chestnut or locust. Thus, using the catkin or 
ament as the criterion, all deciduous trees fall into two 
groups, the amentaceous and the non-amentaceous; the 
latter, as having the most elaborate type of blossom, 
we will consider first. 
In the non-amentaceous group, the flower, by the 
elaboration and size of its parts, and by conspicuous color- 
ing, is more or less ornamental. To one whose casual 
acquaintance with trees is mostly summed up in half a 
dozen species, such as maples, elms, oaks, and hickories, 
it is a surprise to think of any tree—save perhaps an 
apple or cherry—as being covered with bloom, deli- 
cate and brilliant as that of our choice herbaceous 
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