INDEFINITE OR INDETERMINATE INFLORESCENCE. 201 
he 
of Indefnith Indeterminate, or Axillary Inflorescence, depend 
therefore upon the indefinite growth of the primary axis ; while 
the secondary, tertiary, and other axes which are developed 
from it, are terminated by flower-buds. In the Definite or 
Determinate Inflorescence, on the contrary, the primary ayis is 
terminated at an early period by the production of a flower-bud ; 
such an axis has therefore a limit at once put to its growth in 
an upward direction, and hence the names of Definite, Deter- 
minate, or Terminal, applied to it. Each of these primary 
divisions presents us with several modifications, which we now 
proceed to describe. 
1. INDEFINITE, INDETERMINATE, OR AXILLARY IJNFLORES- 
cENCE.—The simplest kind of inflorescence in this class is that 
presented by such plants as the Pimpernel (jig. 394), in which 
solitary flowers, b, b, are deve- 
loped in the axils of what are 
commonly regarded as the or- 
dinary foliage leaves of the 
plant, a, a, although properly 
leafy bracts, the primary axis 
continuing to elongate in an 
upward direction and bearing 
other leaves and flowers; the 
flowers are then said to be 
seer eee enitlary. Wilen Fig. 412. Whorled leafy bracts and 
such flowers are arranged mn solitary axillary flowers of Mare’s Tail 
whorls round the stem, as in (Hippuris vulgaris). 
the common Mare’s Tail, each 
flower being axillary to a leafy bract (jig. 412), they are said to 
be whorled. 
When a number of flowers instead of a single one are de- 
veloped upon anelongated, shortened, or dilated, peduncle placed 
at the extremity of a branch, or in the axil of a bract, a number 
of kinds of inflorescence arise. All these depend upon the extent 
to which the floral axis branches, the mode in which the branch- 
ing takes place, the comparative lengths of the flower-stalks, 
and other subordinate circumstances. It will be convenient to 
describe these various modifications under two heads—Ist, those 
kinds of Indefinite Inflorescence with an Elongated Primary 
Axis ; and 2nd, those witha Shortened or Dilated Primary Axis. 
In all kinds of indefinite inflorescence it will be found that 
the flower-buds always open in succession from the base to the 
apex if the axis is elongated (jigs. 414 and 422), hence these 
inflorescences have been also called acropetal or ascending ; or 
from the circumference towards the centre if the axis is short- 
ened or dilated (jig. 428), therefore such forms are also called 
centripetal. This acropetal or centripetal order of expansion 
necessarily arises from the mode of development of such kinds 
of inflorescence ; thus, the flower-buds situated at the base of an 
Fic. 412. 
