386 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 
same number; stamens twice as many, in two whorls; pistil of 5 united carpels (some- 
times more or fewer); fruit a capsule of various forms, 3 to 12-celled, separating at ma- 
turity into nutlets containing the seeds. 
KEY TO THE GENERA. 
Spreading heavy-scented shrub with 2-foliolate ever- 
green resinous leaves..............-2---20-2-0- 1. CovILLEA (p. 386). 
Trailing prostrate herbs with several pairs of leaflets, 
neither resinous nor evergreen. 
Fruit with several strong sharp spines............ 2. TRIBULUS (p. 386). 
Fruit merely tuberculate, not spiny.............. 3. KALLsTROEMIA (p. 386). 
1. COVILLEA Vail. CREosOTE BUSH. 
Erect, spreading, strongly scented, evergreen, resinous shrub 2 meters high or less 
with 2-foliolate leaves and numerous rather small, bright yellow flowers; leaflets 
small, 5 to 10 mm. long, inequilateral; flowers solitary on short axillary peduncles; 
sepals unequal, caducous, yellow; petals obovate to spatulate, twisted like the blades 
of a propeller; stamens inserted on the 10-lobed disk, the filaments winged below; 
fruit a densely hairy spheroidal capsule breaking into 5 indehiscent nutlets. 
1. Covillea glutinosa (Engelm.) Rydb. N. Amer. Fl. 25: 108. 1910. 
Larrea glutinosa Engelm. in Wisliz. Mem. North. Mex. 93. 1848. 
TYPE Locaity: ‘‘Olla and Fray Cristobal,’’ New Mexico. Type collected by Wis- 
lizenus in 1846. 
RanGeE: Western Texas to southern California and southward. 
New Mexico: From the south side of the Black Range to Socorro and Tularosa, and 
southward. Dry plains, in the Lower Sonoran Zone. 
A characteristic shrub of the mesas in the southern part of the State, where the 
people most often call it ‘‘greasewood.’’ The native people call it ‘“‘hediondilla.”’ 
2. TRIBULUS L. Burnvut. 
Trailing annual with odd-pinnate leaves and small yellow flowers followed by a 
spiny fruit somewhat resembling a sandbur; leaflets about 5 mm. long, oblong, acute, 
4 to 6 pairs; flowers solitary on axillary peduncles, pale or bright yellow; stamens 10, 
hypogynous, the filaments not winged; pistil of 5 carpels, surrounded by an urceolate 
disk; fruit 5-angled, separating at maturity into 5 bony, reticulately veined carpels, 
each bearing 1 to 3 stout spines and divided interiorly into 3 to 5 1-seeded cells. 
1. Tribulus terrestris L. Sp. Pl. 387. 1753. 
Type Locauity: ‘‘Habitat in Europa australi ad semitas.”’ 
Rance: A native of Europe, introduced into many parts of North America. 
New Mexico: Gl6rieta; Kingston; Mesilla Valley; Deming; Nara Visa; Filmore Can- 
yon; Hillsboro. 
A pernicious weed, introduced into many parts of North America from Europe. 
The spines of the fruit are almost as sharp as tacks and will penetrate the soles of 
shoes. They are a constant danger to rubber tires, too, growing by roads as they do. 
3. KALLSTROEMIA Scop. 
Trailing annuals or perennials, closely resembling the last, but with usually larger 
flowers with orange or bright orange petals, and never spiny, merely tuberculate- 
roughened fruit; sepals 5 or 6, mostly persistent and accrescent in age; petals 4 
to 6, caducous; stamens 10 or 12, the filaments not winged; carpels 8 to 12, consisting 
of usually 1-seeded, bony nutlets falling from a persistent central column, 
