Trihulus. ZYGOrHyLLACE/E. gi 



Order XX HI. ZYGOPHYLLACE^. 



Distingiiislicd from the allied orders by the opposite comj.ound Ir.ivoR, with in- 

 terposed stipules and entire dotless leaflets. — Flowers perfect, regular or nearly so, 

 completely symmetrical, the i)art8 in fives or rarely in fours. Sepals distinct or nearly 

 so. Petals hypogynous, in ours imbricated in the bud. Stamens as many or more 

 commonly (in all ours) twico aa majiy as the potids and inserted with thom, in two 

 sets : fihuuents distinct, often appendaged with a scale on the inner side. Ovary of 

 4 or 5 carpels (rarely 2 or 3), but sometimes twice as many cells, and terminal style 

 only one: stigma 5- lO-lobnd. Ovules anatropous, pendulous. Fruit dry. Seeds 

 with a large embryo, straight or nearly so, with flat or broad cotyledons, with or 

 without some albumen. — Herbs, shrubs, or (in Guaiacmn) small trees, Avith very 

 hard and acrid-bitter resinous wood; a few with simple leaves: stipules often 

 spineseent: flowers solitary, on lateral or terminal naked peduncles. 



An order of 17 gonora and barely a luindrcd .species, of tropical and warm-temperate countries, 

 on this co.ituient clnefly Mexican and South American, four repre.senUtives, belonRinK to thre^ 

 genera, barely reachmg California. 6 6 i.u co 



J' ?I^"\"^" /''''^^««j^^'"!Pflypi""''ite, 6-10-foliolate. Fruit tuberculate. Herbs. 



2. Fagonia. Leaves 3-foliolate. Fruit nearly .smooth. Herbaceous 



3. Larrea. Leaves 2-foliolate. Fruit densely hairy. A he.avy-sccnt«d shnib. 



1. TRIBULUS, Linn. 

 Sepals 5, mostly per.si.stent. Petals 5, fugacious. Disk annular, 10-lobed. 

 Stamens 10; the alternate iilaments a little shorter and with a gland at base on the 

 outer side. Ovary 5 - 12-celled ; cells 1 -5-ovuJed. Fruit lobed, separating from 

 tlie persistent axis into 5 to 12 indehi.scent 1-seeded tuberculate or winged or 

 spinose carpels. Seeds without albumen. — Loosely branclied liairy prostrate herbs; 

 with abruptly pinnate opposite leaves (the alternate ones smaller or wanting), and 

 solitary apparently axillary white or yellow flowers. 



Species 15 or more, natives of the warmer regions of botli hemispheres. Our species are 

 annuals, belonging to the section Kalhtra^mia, having the outer stame. s adnate at lie to th^ 

 petals, the ovary 10 -12-celled and 10- 12-ovuled. A true Trrbulus, Z\T^rJ.iT(^liM 

 mcus, Watson, Proc. Am. Acad. xi. 125), from the western side o the Oul^orCalifornTa^hL 

 very small flowers and deeply 6-lobed fruit, the cari>els with 4 or 5 stout tuWrcle.s on the J^k 



1. T maximus, Linn, stems at length elongated : leaflet^s .T or 4 pairs ovate- 

 oblong, 3 to G lines long, more or less obli-pie: peduncles thickened upward, a half 

 to an inch long : sepals very hairy, linear, acuminate, two lines long : petals a half 

 longer: fruit two lines high, beaked by a stmit style about as long the carpels 



roughly tulierculate. — /ra/A^/ro-m/a Wif/Tjwa, Torr. it f^rav Fl i Tl ■ (Jrav (!en 

 III. ii. 117, t. 140. ' ' -''.'• 



MexiVraIr.Tb?w'7!'i'" ^"t?- ^°^'""" ^"•*'^*' •^•■y """P'"" ''"'^''^'^ ♦" T""'-'- '^"'i through 

 Mexico and the W . Lidics. The specific name is in no respect appropriate. 



2. T. grandiflorus, P.enth. &: Hook. Ilispirl with usuallv longer and more 

 spreading hairs: leallets 4 to fi pairs: peduncles m.-re elnngated • .sepals 3 to G 

 lines long, the petnls usually twice hwigrp : fruit nither more sharply tuborrulato, 

 tin beak 3 to f, lines long. — den. PI. i. 2GL Knihinrmm qrmulffhm. Torn in 

 Omy, PI. Wright, i. 28. ... 



In the Oila Valley. Arizona, and i^robably in Sonthcasfern Talifornia ; ranging to Now Mexico. 

 Sonora .Tud I,ower ( nhfornia. * iio*iiA., 



