388 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 



1. Koeberlinia spinosa Zucc. Abh. Akad. Wise. Mi'mchen 1: 358. 1832. 



Type locality: Mexico. 



Range: Southern New Mexico and Arizona, western Texas, and adjacent Mexico. 



New Mexico: Warm Spring; plains south of the White Sands; west of Dona Ana 

 Mountains; Black Range; Hachita; Organ Mountains; north of Derning. Dry plains 

 ami hills, in the Lower Sonoran Zone. 



A very spiny, much branched shrub, usually branched from the base, but some- 

 times with a definite trunk. It is sometimes called "crown of thorns." 



76. MALPIGHIACEAE. Malpighia Family. 



1. JANUSIA A. Juss. 



Low twining perennial with woody stems; leaves opposite, narrowly lanceolate, 

 1 to 3 cm. long, pubescent on both surfaces; sepals 5; petals 5, yellow, turning reddish 

 brown; stamens 5; styles united; fruit a samara, 9 to 12 mm. long. 



1. Janusia gracilis A. Gray, PI. Wright. 1: 37. 1852. 



Type locality: Mountains east of El Paso, Texas. 



Range: Western Texas to southern Arizona and adjacent Mexico. 



New Mexico: Parkers Well; Tortugas Mountain. Dry hills, in the Lower Sonoran 

 Zone. 



77. RUTACEAE. Rue Family. 



Aromatic shrubs or low herbaceous perennials; leaves alternate, simple or com- 

 pound, glandular- punctate; flowers perfect or by abortion polygamous, in cymes 

 or short raceme-like clusters, not conspicuous; sepals 4 or 5, small; petals of the same 

 number, dull-colored, small; stamens of the same or twice the same number, inserted 

 on a hypogynous disk; pistil of 2 or 3 united carpels; fruit a capsule or samara. 



KEY TO THE GENERA. 



Low herbaceous plants; leaves small, simple 1. Rutosma (p. 388). 



Shrubs; leaves 3 to 10-foliolate, with large leaflets. 



Fruit a circular samara; leaves 3-foliolate 2. Ptelea (p. 388). 



Fruit a 2-celled pod without wings; leaves pal- 



mately 5 to 10-foliolate 3. Astrophyllum (p. 390). 



1. RUTOSMA A. Gray. 



Perennial herb, 30 cm. high or less, with small linear sessile leaves and inconspic- 

 uous flowers; fruit of 2 divergent carpels. 



1. Rutosma purpurea Woot. & Standi. Contr. U. S. Nat. Herb. 16: 143. 1913. 



Type locality: On an arid rocky slope at Bishops Cap at the south end of the 

 Organ Mountains, New Mexico. Type collected by Wooton, March 30, 1905. 



Range: Western Texas to southern Arizona. 



New Mexico: San Andreas Mountains; Organ Mountains; Carrizalillo Mountains; 

 south of Hillsboro; Mangas Springs. Dry rocky hills, in the Lower and Upper Sonoran 

 zones. 



2. PTELEA L. Shrubby trefoil. 



Branching shrubs, 2 to 3 meters high, with smooth dark-colored bark on the old 

 stems and greenish or yellow or reddish brown bark on the young stems, strongly 

 scented; leaves 3-foliolate, the leaflets oblong-lanceolate or rhombic, the terminal 

 one attenuate at the base, the lateral ones inequilateral, pellucid-punctate; flowers 

 polygamous, greenish yellow, small, cymose; sepals, petals, and stamens 4 or 5, the 

 last abortive in the pistillate flowers; ovary 2 or 3-celled; fruit a flattened, 2 or 

 3-seeded, disk-shaped, reticulate samara. 



