DICOTYLEDONS: ARCHICHLAMYDEZ 283 
dicecious (§ 137) and wind-pollinated. A very character- 
istic flower-cluster occurs in many of these forms, being a 
spike-like cluster, but having conspicuous scales or bracts 
subtending individual flowers or small groups of flowers. 
It is called the 
ament or catkin; 
and familiar illus- 
trations are found 
on willows (Fig. 
278), cottonwoods, 
birches, and alders 
(Fig. 279). Both 
staminate and _ pis- 
tillate flowers, or 
only one kind, may 
be in aments. 
In higher fami- 
lies with more con- 
spicuous and usual- 
ly insect-pollinated 
Fic. 278.—Catkins of willow: A, staminate; B, pis- 
tillate. 
flowers, other common trees occur, as the tulip-tree (white 
Fic. 279.—Catkins of alder; A, branch with 
staminate (n) and pistillate (m) catkins; 
B, pistillate catkin in the next year (when 
the seeds are ripe).—After WaRMING. 
poplar), magnolia, lin- 
den, maple, buckeye, 
box-elder, locust, sweet- 
gum, and tupelo (black- 
gum); and among the 
Sympetale the ash be- 
longs. The very names 
of these trees suggest 
the characteristic forms 
of our great deciduous 
forest, which once ex- 
tended in almost un- 
broken sweep from the 
prairies to the Atlantic 
