182 =~ FLOWERING PLANTS 
same branch are above them, and catch the pollen carried by 
the wind from the staminate catkins of another branch. If a 
staminate catkin is examined it will be seen to consist of 
scales fairly close together, each containing three flowers ; 
each flower shows two forked stamens. ‘The pistillate catkins 
have the scales much more closely packed together, and each 
has likewise three flowers. The flower has no perianth, and 
consists of two carpels, as may be easily seen from the two 
styles. The fruit is a nut, which is formed in the following 
way: the ovary is 2-celled, and has to begin with one ovule 
in each cell; then one cell and one ovule become suppressed, 
the other ovule developing into a seed. The wall of the 
ovary becomes hard. Each scale of the pistillate catkin thus 
supports three broadly-winged nuts, formed from the three 
flowers ; the wings of the nuts are organs of dispersion. 
The Alder is a much darker tree than the Birch, and 
122 198 usually grows _ by 
: _ streams or in wet 
woods and _ pastures. 
The staminate cat- 
kins are two or three 
together, and hang 
down ; the pistillate 
ones of the same 

Fic, 122.—SraMInaTE FLower, “AWER. branch are above 
p, perianth. h os : 
Fic. 123.—Pisr1ntaTe FLowEr, ALDER. U ee PN Seek 
c, scale covering 2 flowers ; b, scales be- spikes. After the 
longing to flower. fruit is formed the 
scales become hard and woody, and remain on the tree during 
the winter-—at any rate, long after the nuts have fallen 
(Plate VUL., Fig. 120). 
Kach staminate flower consists of a perianth and 4 stamens, 
the whole being situated, with two other flowers of similar 
structure, in a scale. ; 
Vig. 123 shows two pistillate flowers situated in a scale (¢) ; 
each single flower has 2 bracts, and consists of 2 carpels, as 
may easily be seen from the 2 styles. 
