¢ Le! “a er ot > hee rp) 4 l a . a Se oe ae “SOS 2 a eee eee * 
' me ak i: e . ye ‘ ¥ *. ‘ >, - ~~ 
pn hn > d 372 Tt Reh - 7 F - ts ffec, Vite ee ote > ~ * 
a Voss een Se fe be SP oh mete OE See ae 
Pi e , > La y + 4 
7 
120 © Structural and Physiological Botany. 
the marginal flowers of each capitulum are larger and more — 
conspicuous than the internal ones, and the capitulum is 
then said to be vayed [the outer flowers being termed flowers 
or florets of the ray, the inner ones flowers or florets of the disc|, — 
as in the chamomile (Fig. 214), single aster, marigold, &c. — 
The wmbel resembles the capitulum in the fact of the stem 
terminating in a number of flowers, but each separate flower 
is stalked. The umbel is szmp/e when the main stem or 
peduncle ends in a number of separate stalked flowers, as 
in the cherry (Fig. 220), compound when it branches into a 
number of secondary umbels or umbellules (Fig. 221), [as in 
the majority of genera of 
Umbelliferze]. The main 
umbel is generally sur- 
rounded at its base by a 
whorl of bracts, again 
called an zzvolucre, while 
the whorl surrounding 
each of the secondary 
umbels is an zzvolucel or 
Fic. 221.—Compound umbel of fool’s parsley, partial involucre, Either 
ie thusa cynapium ; common involucre want- of the two may, however, 
ing; involucels of three leaves each. ; 
be wanting, or may con- 
sist of a smaller or larger number of leaves. Thus the carrot 
has both involucre and involucels, each consisting of a large 
number of bracts ; the fool’s parsley, “thusa cynapium (Fig. 
221), has involucels, but no general involucre; the fennel 
neither one nor the other. The length of the separate 
pedicels may vary greatly, so that the umbel becomes 
spherical, hemispherical, or flat ; or it may be rayed like the 
capitulum [as in /Zeracleum, where the outer flowers of each 
umbellule are larger than the inner ones]. 
In the sfzke, the common peduncle or rachis bears a 
number of flowers, arranged, in the simple spike (Fig. 222) 
opposite one another, in whorls, or spirally, and sessile, or 
with only very short pedicels ; while, in the compound spike, 
