THE INFLORESCENCE 259 
A Spike is a cluster of flowers, sessile or nearly so, borne in the 
axils of bracts on an elongated rachis. The Mullein and com- 
mon Plantain afford good illustrations. If branches arise from 
the rachis of a spike and bear flowers, a COMPOUND SPIKE results. 
In this type of inflorescence which is seen in Wheat, Rye, Barley 
and many other members of the [iG =a aaa Se 
Grass Family, the branchiscalled | — /¢@@t/ 
the rachilla and the secondary 
inflorescences are termed sprkelets. 
The CaTKIn or AMENT resem- 
bles the Spike, but differs in that it 
is deciduous and usually bears 
only one kind of flowers, stami- 
nate or pistillate, as in the Oak, 
Hazel, Willow, Comptonia, etc. 
The Heap or CAPITULUM is 
like a spike, except that it has the 
rachis shortened, so as to form a 
compact cluster of sessile flowers, 
as in the Dandelion, Marigold, 
Clover, and Burdock. 
The STROBILE is a compact 
spike of unisexual flowers with 
overlapping scales concealing the 
flowers, as the inflorescence of the 
Hop. 
‘ ° Fic. 174.—Photomicrograph of 
The Spaprx is a thick, fleshy longitudinal section through a stami- 
rachis with flowers closely sessile pate catkin of Comptonia asplenifolia 
or embedded on it. It is usually x10, showing catkin axis (ax), 
rhore he Wed elon oy a sensi: St, ore ©) and bract ©). 
or sheathing bract. Examples: Calla, Calamus, Arum triphyllum. 
The raceme, corymb, and umbel, are frequently com- 
pounded through the branching of their pedicels. The com- 
pound raceme, or raceme with branched pedicels, is called a 
Panicte. Examples: Brayera, Yucca and the Oat. 
DETERMINATE INFLORESCENCES.—Determinate Anthotaxy is one 
in which the first flower that opens is the terminal one on the axis, 
the others appearing in succession from apex to base or from 
