HOW TO KNOW THE GRASSES 



Figure 353 



TRIBE XIII. TRIPSACEAE 



la. Pistillate spikelets borne in hard, bony beads, each bead on a 

 separate stalk; staminate spikelets protruding on a stalk from the 

 opening of the bead. Fig. 353. 



JOB'S TEARS Coix lacryma-jobi L. 



Annual; plants coarse, somewhat corn- 

 like, up to 1 m. tall, abundantly branch- 

 ing from the upper nodes. Each peduncle 

 bears a hard, shiny, white, grayish, or 

 black bead, from the upper end of which 

 protrudes a short inflorescence consisting 

 of few joints bearing sessile and pedicel- 

 late staminate or sterile spikelets, in some- 

 what irregular combinations. Staminate 

 spikelets consist of 2 glumes, inclosing 2 

 staminate florets. Within the bead is borne 

 a single pistillate spikelet and 2 slender, 

 tubular, sterile spikelets, along with the 

 stalk of the staminate inflorescence. The 

 stigmas protrude from the mouth of the 

 bead. The staminate inflorescence breaks 

 away and the beads fall from the plant 

 when ripe. Job's tears is cultivated as a curiosity, and for the "beads," 

 which are used in rosaries and jewelry. The plants may be found 

 in the wild in the southern states. Introduced from the tropics of the 

 Old World. Late summer. 



lb. Pistillate spikelets borne in spikes or on cobs, never separately . . 2 

 2a. Staminate spikelets borne at the tip and pistillate spikelets at the 

 base of the same spike: pistillate portion of the spike hard and 

 bony; husks not present. Fig. 354. 



GAMA GRASS TTipsacuzn dactyloides L. 



Perennial; in large clumps, from thick rhi- 

 zomes. The plants reach 2 — 3 m. in height. 

 The spikes are borne singly or 2 — 3 together 

 at the tips of long leafless peduncles. The 

 basal portion of each spike consists of a ser- 

 ies of hardened, smooth, hoUowed-out joints, 

 each nearly inclosing a single pistillate spike- 

 let. These joints break apart readily when 

 ripe. The upper portion of each spike is 

 made up of a series of joints, each bearing 

 2 sessile staminate spikelets. This portion 

 of the spike is shed whole when the pistillate 

 rachis breaks up. Gama grass is a close 

 relative of corn and has been experimentally 

 crossed with it. The plants are leafy and 

 may produce some forage, but they are sel- 

 dom abundant. River banks and moist ground. June — October. 



Figure 354 



184 



