XXVI. ZYGOPlIYLLEiE. 287 



A small Order, nearly allied on the one hand to Malpif/Mace^, on the other to Geraniacp(B 

 and Ralacece, dispersed chiefly over the subtropical regions of both the Old and New 

 World, and most abundant in dry desert or saline regions. The three Australian 

 genera are all cominoD to Africa and Asia, and one of them extends also to Europe and 

 America. 



r 



Leaves pinnate. Petals 5, flat. Fruit of 5 hard, indehisccut, usually 



prickly or tubcrcidate cocci 1. Trtbulus. 



Leaves simple. Petals 5, concave. Fnut a drupe with a hard 



1-secdcd nut 2. :n-itkakia. 



Leaves with 2 leaflets or lobes. Petals 4 or 5, flat. Fruit a 4- or 



5-angled or winged capsule 3. ZvooriiYLLUM. 



1. TRIBULUS, Liun. 



{TribulopU, 31. Br.) 



^ Sepals 5, rarely 6, Petals as many, flat. Disk annular, 10-lobed or 

 sinuate, witli a ffland at the base of each of the inner stamens, alternatiuf? 



witli the petals. Stamens twice as many as petals, the filaments filiform, 

 without appendages. Ovary of 5 or sometimes more cells, with 1 or 2 to 5 

 s^iperposed ovules in eacli cell. Fruit separating into as many cocci as carpels, 

 hard, indehiscent, and each usually bearing 2 or more prickles or tubercles. 

 — Herbs, usually prostrate or divaricate and hairy. Leaves abruptly pinnate, 

 opposite, with one of each pair smaller than the other, or sometimes abortive 

 or all alternate. Stipules small, lanceolate, or falcate. Pedicels solitary in 

 the axil of the smaller leaf of each pair, or opposed to the leaf when alternate. 

 Flowers white or yellow. 



The genus is dispersed over the greater part of the tropical and \yarm regions of the 

 globe, extending into Europe and N. America. Of the Australian spceics, one is ahuudaut 

 ni Asia, Africa, and S. Europe, another is most common in tropical America, less so in Asia 

 and Africa, and the other 9 arc all endemic. 



leaves, at least the upper ones, opposite. Glands of the disk not 

 very prominent. Ovules 2 or more in each cell. {Tribuhts 

 proper.) 



Cocci rounded at the back, without angular or winged edges. 

 Cocci with 2 or 4 prickles, rarely minute or deficient. 

 Leaves almost all opposite. Ovules 3 or 4 in each cell. 



Annual. Flowers small. Petals about i in \> T. ierredrh. 



■ Perennial. Flowers large. Petals about i in. ... 2. T, cistoides. 

 Lower leaves alternate. Ovules 2 in each' cell. Flowers 



lar'^e 3. 71 ranunculi/torus^ 



Cocci covered with numerous ueaily equal prickles .... 4. 7. Af/strlx. 

 Cocci with prominent almost winged angles, and 2 prickles on 



the back between them 5. 7. vwcrocarpus. 



Cocci broadly winged at the andes, without prickles. 



Plant glabrous except the inside of the sepals. Cocci smooth 6. T, plaif/phrus. 



Plant hirsute. Cocci strongly reticulate on the bnck and 



sides 1. T. hirsute. 



I^^'ivcs (except T. minnftts) all ahemate. Glands of i^it disk 



prominent. Ovules solitary. Fruit pyramidid, the cocci 



^^ith 2 or 4 tubercles or small prickles below the middle. 



{Tribulopu^^ R. Br,) 



Leaflets 2 pairs, the lowest much smaller. Perfect stamens 



Usually 5 8. T. peniaiumts. 



