112 



MANUAL OF BOTANY 



Fig. 212. 



Fig. 213. 



are simply modifications of the spike. These are the Amentum 

 or Oathin, the Spadix, the Locusta or Spihelet, and the Strobile, 

 a. The Amentum or Catkin. — This is a kind of spike which 

 usually bears unisexual flowers — that is, only staminate (fig. 214), 

 or only pistillate {fi,g. 215) ones. The axis or rachis is usually of 

 a very weak character, so that the catkin is pendulous. The 

 flowers of an amentum are also ustially separated from one 



another by scaly bracts. The 

 staminate catkins commonly fall 

 off in one piece, soon after the pro- 

 cess of flowering. The bracts have 

 sometimes one, or at other times 

 several flowers in their axils. All 

 plants with this kind of inflores- 

 cence are called amentaceous or 

 amentiferous. Our trees afford 

 numerous examples, as the Oak, 

 Willow, Birch, and Poplar. 



f. The Spadix is a spike with 

 a succulent axis in which the 

 individual flowers have no special 

 bracts, but the whole inflorescence 

 is enclosed in that variety of bract 

 which is called a spathe. This is 

 well seen in the Cuckoo-pint (fig. 

 201), where the spadix included 

 in the spathe bears staminate and 

 pistillate flowers, the latter being 

 nearest its base. The term spadix 

 is also usually applied to a suc- 

 culent spike, whether enveloped in 

 a spathe or not, as in the Sweet 

 Flag (Acorus Calamus). 



g. The Locusta or SpiJcelet. 

 This name is given to the partial 



inflorescence of Grasses (fig. 203), and of plants of the Sedge 

 Order. In Grasses it is a spike with a few flowers, and 

 these destitute of a true calyx and corolla, their place being 

 occupied hj palece cr pales (fig. 203, ps, pi), and the whole in- 

 florescence surrounded at the base by one or two empty bracts 

 (glumes), gl, gl. These spikelets may be either sessile on the 

 elongated peduncle or rachis (fig. 219), as in the Wheat, or they 

 may be placed on a more or less branched axis, as in the Oat 



Fi<j. 212. Spike of a species of Rib- 

 grass (Flantago'). FiiJ. 



Spike of Vervain ( Verhena). 



213. 



