108 NORTH AMERICAN FLORA [Volume 25 



3. PORLIERIA R. & P. Prodr. 55. 1794. 



Shrubs with short stunted branches. Leaves opposite, abruptly pinnate, approximate 

 on the short branches. Leaflets linear or oblong, entire. Stipules mostly persistent, in the 

 South American species spinescent. Flowers mostly solitary, from the axils of minute 

 bracts. Sepals mostly 5, imbricate, unequal. Petals 5, obovate or oblanceolate, scarcely 

 unguiculate. Stamens 10, inserted on a small disk ; filaments filiform, with scale-like 

 appendages at the base. Anthers oblong. Pistils of 2-5 carpels. Ovary obovoid or sub- 

 globose, stipitate, deeply 2-5-lobed and 2-5-celled. Ovules 2-4 in each cell, pendulous. 

 Fruit coriaceous or somewhat fleshy, each cell with a single, kidney-shaped seed. Embryo 

 straight or curved. 



Type species, Porlieria hygromctrica R. & P. 



1. Porlieria angustifolia (Engelm.) A. Gray, PI. 

 Wright. 1 : 28. 1852. 

 Guaiacum angustifolium Engelm. in Wisliz. Tour Northern Mex. 113. 1848. 



A shrub or small tree with very knotty and crooked, at length glabrous branches; 

 stipules subulate, setaceous, somewhat subspinescent, purplish ; petioles pubescent ; 

 leaves 1-3 cm. long; leaflets in 5-8 pairs, oblong-linear, 8-12 mm. long, 2-3 mm. 

 wide, apiculate, reticulate, glabrous, coriaceous ; flowers mostly single in the axils of 

 the leaves ; peduncles pubescent ; sepals 5, obtuse, the outer ones much smaller ; petals 

 5, dark blue-purple, about 1 cm. long; filaments with a small crenate scale at the base; 

 ovary 2-lobed, pubescent, the attenuate style somewhat 2-sulcate (or rarely the ovary 3-4- 

 lobed, the 3-4 styles cohering or free); fruit bivalved, flat, obcordate, rarely 3-4-valved ; 

 seed ovate, yellowish-brown, enclosed in a thick, fleshy, scarlet or orange-colored aril. 



Type locality : Parras, Coahuila. 

 Distribution : Texas and northern Mexico. 

 Illustration : A. Gray, Gen. 111. pi. 149. 



4. COVILLEA Vail, Bull. Torrey Club 22 : 229. 1895. 



Larrea Cav. Anal. Hist. Nat. 2 : 119. 1800. Not Larrea Ortega, 1797. 



Low, evergreen, strong-scented, balsamiferous shrubs, with usually much branched 

 stems and nddose, articulate, distichous and mostly attenuate branchlets. Leaves opposite, 

 equal, consisting of a single pair, rarely of several pairs of inequilateral leaflets which are 

 more or less united at the base, sessile or the common petiole very short ; stipules persist- 

 ing. Peduncles interstipular, short, terminal, 1-flowered. Sepals 5, imbricate, unequal, 

 caducous. Petals 5, yellow, obovate or lanceolate-spatulate, hypogynous, more or less 

 unguiculate, longer than the sepals. Disc small, 10-lobed. Stamens 10, inserted on the 

 base of the disc. Filaments filiform, connate below with the outside of a 2-cleft and some- 

 times laciniate-toothed membranaceous scale. Anthers oblong. Pistil of 5 united carpels. 

 Ovary short-stipitate, globose, pilose, 5-celled, the cells alternate with the petals. Styles 

 united, sometimes separable. Stigmas 5, minute. Ovules usually6 in each cell, pendulous 

 in pairs from its inner angles, anatropous. Fruit villose or tomentose, globose or obovoid, 

 5-angled, separating into 5 indehiscent carpels. Seed solitary by abortion, oblong, some- 

 what incurved; cotyledons narrowly oblong, flattish.. 



Type species, Larrea nitida Cav. 



Leaflets obliquely lanceolate, 3-nerved ; fruit globose-elliptic, scarcely stipitate, 

 its hairs as long as the diameter of the carpels or longer. 1. C. glutinosa. 



Leaflets obliquely ovate, 4-5-nerved ; fruit obovoid, distinctly stipitate, its 

 hairs shorter than the diameter of the carpels. 2. C. tridentata. 



1. Covillea glutinosa (Engelm.) Rydberg. 



Zygophyllnm califoi~nicum Torr. & Fr£m. in Frem. Rep. 257; hyponym. 1845. 



Larrea glutinosa "Engelm. in Wisliz. Tour Northern Mex. 93. 1848. 



Covillea divaricata Vail, Bull. Torrey Club 22 : 229. 1895. Not Larrea divaricata Cav. 1800. 



A diffusely branched resinous shrub, 1-3.5 m. high, with grayish bark ; stems densely 

 leafy, angled, silky-pubescent ; stipules reddish, very small, subulate ; leaves nearly sessile ; 



