ZYGOPHYLLEiE. (ZYGOPHYLLUM FAMILY.) 185 



(rarely 4J sejpals and petals, irnbricated in the hud (rarely 

 convolute,) stamens as many or twice as many as the petals, 

 usually with a scale at hase — Lobes of ovary as many as 

 sepals, rarely more ; cells 2- go - (rarely 1-) ovuled, some- 

 times divided by transYerse partitions ; ovules aiiatropoiis, 

 pendulous or ascending. Style 1, from axis (rarely 5,) stigma 

 simple. Fruit a septicidal capsnle, composed of carpels which 

 separate at length from the axis. Seeds with or without 

 albumen. Embryo straight, radicle superior. 



* Embryo without albumen, 



t Fruit separating into indehiscent carpels. 



1. TRIBULUS. Prostrate herbs with pinnate leaves and prickly fruit, 



t t Fruit an inversely pear-shaped, unarmed drupe, icith bony endocarp, 



2. NITRARIA. Shrubs with fleshy leaves, growing m salt marshes 



* * Embryo albuminous. 



3. SEETZEENIA. Petals 0. Desert perennial herbs. 



4. ZYGOPHYLLUAl, Petals 4-5. Stamens with a scale at base. Stipules not spinescent. 



5. FAGONIA, Petals 4-5. Filaments naked at base. Stipules spinescent. 



1. TRIBIJL.US, L. Tmbulus. 



Sepals 5. Petals 5, fugacious. Disk annular. Stamens 10 (rarely 

 5) inserted at base of disk, shorter than the petals, alternating with 

 them, furnished with a gland at base. Ovary sessile, 5-celled, cells 

 transversely divided. Style 1, stigma 5-rayed. Ovules 1-5, placed one 

 above another in the cells. Fruit composed of bony cells, with a 

 prickly or winged-prickly back — Annual, prostrate, loosely branched 

 herbs, with flowers in the forks of the branches or in the axils, the 

 leaves abruptly pinnate, or (by abortion) imparipinnate. 



1. T. bimueronatu§, Viv. .3 to .5, appressed-canescent. 

 Petals obovate, somewhat longer than calyx ; stamens 5, rarely 10 ; 

 stigma capitate or ovate, as long as or longer than the style ; carpels 

 appressed-hairy or canescent, round at l/acJc, rough-warty, with 4 prick- 

 les, the lower often reduced to tubercles — Spring — Sinai. 



Fig. 78. 



Leaf and fruit of T. terrestris, 

 ^7 



