Family 9. ZYGOPHYLLACEAE 



By Anna Murray Vail and Per Axel Rydberg * 



Perennial caulescent herbs, shrubs, or rarely hard-wooded trees, often strong- 

 scented and yielding a bitter and acid gum-resin. Branches commonly with 

 articulate nodes. Leaves opposite or alternate, simple, digitate, or more com- 

 monly pinnate, the leaves or leaflets entire, often inequilateral, epunctate. 

 Peduncles 1 or 2, borne in the axils of the stipules which are interpetiolar 

 when the leaves are opposite. Flowers perfect, regular or nearly so. Calyx 

 of 5 (rarely 4 or 6) sepals, free or rarely connate at the base, imbricate or rarely 

 valvate. Corolla hypogynous, of 5 (rarely 4 or 6) free petals that are imbri- 

 cate, valvate, or convolute. Androecium of twice as many stamens as petals 

 in 2 series (rarely thrice the number); filaments subulate, naked or appendicu- 

 late at the base, those opposite the petals exterior, larger than the inner ; 

 anthers versatile, introrse, longitudinally dehiscent. Gynoecium of usually 

 2-5 united carpels. Ovary sessile or short-stipitate, 2-5-celled, rarely 8-12- 

 celled, sulcate, angled or winged, terminated by a common style and entire, 

 clavate or lobed papillose stigma. Ovules solitary or several in the cells, pendu- 

 lous or ascending. Fruit capsular, variously angled, or splitting into few to 

 several, smooth or spinescent nutlets (in some exotic species drupaceous). 

 Seeds with or without endosperm. Embryo straight or curved; cotyledons 

 fleshy, linear or oblong. 



Leaves compound, or if by reduction unifoliolate or simple, not pinnatifid. 

 Leaves mostly opposite, not odd-pinnate. 



Leaves digitately 1-7-foliolate ; stipules spiny ; stamens with scale-like 



appendages. 

 Leaves abruptly pinnate ; stipules in ours not spiny. 

 Shrubs or trees with endosperm. 



Fruit not woolly ; corolla blue or bluish. 



Stamens without scale-like appendages at the base ; stipules 



deciduous. 

 Stamens with scale-like appendages at the base ; stipules 

 persistent. 

 Fruit woolly ; corolla yellow ; stamens with scale-like appendages. 

 Herbs without endosperm ; corolla mostly yellow ; stamens without 

 scale-like appendages. 

 Fruit dividing into 5 (by abortion sometimes fewer) carpels, each 



with 3-5 one-seeded compartments, spiny. 

 Fruit dividing into 8-12 (twice as many as the original carpels) 

 one-seeded nutlets, merely tubercled. 

 Leaves mostly alternate, odd-pinnate, or by reduction uni-foliolate or 

 simple. 

 Stamens not appendaged ; carpels many-seeded, tomentose. 



Flowers solitary, purplish ; petals and sepals 4 ; stamens 8 ; leaves 



3-17-foliolate. 

 Flowers clustered, yellowish ; petals and sepals 5 ; stamens 10 ; 

 leaves 1- (rarely 3-5-) foliolate. 

 Stamens appendaged at the base; carpels one-seeded, villous; corolla 

 yellow ; leaves simple. 

 Leaves simple, alternate, pinnately dissected into linear divisions. 



*The manuscript was prepared several years ago by Anna Murray Vail, but lately 

 revised and enlarged by PER Axel Rydberg, in view of much recent material, especially 

 in the genera Fagonia and Kallstroemia. 



Volume 25, Part 2, 1910] 103 



