INDBEINITE INFLOEESCENCB. 



179 



surrounded by a sheathing bract or spathe, and then it constitutes a 

 spadix, which may be simple, as in Arum maculatum (fig. 260), or 

 branching, as in Palms. A spike bear- 

 ing female flowers only, and covered 

 with scales, is either a strobilus, as in 

 the Hop ; or a cone, as in the Fir (figs. 

 217, 218). In grasses there are usu- 

 ally numerous sessile flowers arranged 

 in small spikes, called Locustm or 

 spihelets, which are either set closely 

 along a central axis, or are produced 

 on secondary axes formed by the 

 branching of the central one; to the 

 latter form the term Panicle is applied. 



Fig. 261, 



Fig. 262. 



Fig. 263. 



If the primary axis, in place of being elongated, is contracted. 



Fig. 261. Several umbels, o' o' o' &, of Aralia racemosa. a. General Axis or the apex of 

 the branch terminated by a single umbel farther advanced than the rest, a' a' a' a', Axes 

 arising from it, which are secondary as respects the general axis, a ; each of them bears an 

 umbel,' and as regards this inflorescence they are primary, a" a" a". Secondary axes, or the 

 radii of the umbel. & 6 &, Bracts placed alternately on the general axis, d. Shows a double 

 budsproceeding from the axU of;[one of these bracts, and thus giving rise to two stalked or 

 stipitate umbels, i i i, Vertlcillate bracts, forming involucres at the base of the radii of the 

 umbels. Fig. 262. Compound umbel of Carrot {Daucus Garota). a'. Primary axis 



shortened and depressed, so as to present a convex surface, a" a". Secondary axes, or radii 

 of the general umbel, each ending in a partial umbel or urabellule, o" o" o" o". a!" a"', 

 Tertiary axes of radii of the partial umbels or umbeUules. i', Pinnatipartite bracts, form- 

 ing the general involucre, i" i". Simple bracts, forming the partial involucre or involucel. 

 Fig. 263. Capitulum, Anthodium, or Head of flowers of Scorzonera hispanica. t. Imbricated 

 bracts, forming an involucre. /, Florets or small flowers on the receptacle, having a centri- 

 petal evolution. 



