t f air v4 i 7 f 
4 i ce Cy ) Bas i ite : 
rity ay, ( ae mee ‘ fee ; / , us 
 P . Pky - , t 1 4 d y } ; f i 
=e ) 
The External Form of Plants. IIt 
corolla, the former constituting an outer whorl, which is 
usually green, and the latter an inner whorl, which is usually 
coloured (7.e. not green), (Fig. 199). In other cases, how- 
F IG. 199.--Flower of Sywz- Fic. 200.—Flower of Sisymebrium A lic- 
phytum officinale, with both aria (magnified): k calyx; B corolla ; 
calyx and corolla. S stamens ; St pistil. name 
ever, there is no such contrast between the two whorls. One | ~ 
may be entirely absent, as in the elm [or stinging nettle], — 
or, if both are present, as in Lillacee, [Juncaceze], and 
Fic. 201.—Staminate (4) flower of Cali- FiG.202.—Pistillate( 9) flower of CaZZz- 
triche verna (greatly magnified) with triche verna (greatly magnified). 
two-sickle-shaped bracts. 
Orchidez, they may not materially differ in colour or form ; 
and the term Zerzanth is especially used in reference to these’ 
cases. The essential parts of the flower are the andrecium 
or stamens, and the gvueceum or pistil (Fig. 200, s, St). 
