118 



NORTH AMERICAN FLORA 



[Volume 32 



Leaves sessile or nearly so, broadly rounded or subcordate 

 at the base. 

 Corolla 3-3.5 cm. long; leaf -blades rounded at the base; 



capsule 12-15 mm. long. 

 Corolla 4.2-5 cm. long; leaf -blades mostly subcordate 

 at the base; capsule 5-8 mm. long. 

 Leaves conspicuously petiolate, usually acute or obtuse at 

 the base. 

 Leaf-blades elliptic-oblong, lance-oblong, or lanceolate. 

 Petioles about 8 mm. long; leaf -blades 5-7 cm. long. 

 Petioles 3-6 mm. long; leaf -blades 3-4.5 cm. long. 

 Leaf-blades mostly oval, elliptic-oval, or rounded-ovate. 

 Capsule oval, coarsely 10-costate; corolla-tube twice 



as long as the lobes. 

 Capsule oblong-cylindric, smooth or obscurely 

 costate. 

 Leaf -blades 10-18 cm. long; corolla-tube about as 



long as the lobes. 

 Leaf-blades 5-9 cm. long. 



Corolla-tube about 4 cm. long, almost twice as 



long as the lobes. 

 Corolla-tube about 2.5 cm. long, the lobes of 

 the same length. 

 Corolla 7-16 mm. long; anthers 1.5-2.5 mm. long. 

 Leaves 0.8-1.2 cm. long; pedicels 3-4 mm. long. 

 Leaves 1.5-9 cm. long; pedicels 2 mm. long or shorter. 

 Hypanthium glabrous. 



Calyx-lobes linear or linear -spatulate, obtuse, often 



equaling the hypanthium. 

 Calyx-lobes triangular, acute, half as long as the hypan- 

 thium or shorter. 

 Hypanthium pubescent. 



Leaves glabrous beneath. 



Capsule 2.5^ mm. long; leaf-blades 1.8 cm. long or 



shorter, rounded at the apex. 

 Capsule 4.5-5.5 mm. long; leaf-blades 2-3 cm. long, 

 acute or acutish. 

 Leaves pubescent beneath. 



Leaves acutish, long-petiolate, densely velvety- 

 pilose beneath. 

 Leaves rounded or very obtuse at the apex, long- 

 petiolate, with tufts of hairs beneath along the 

 costa. 

 Corolla pubescent outside, 1.5-2 cm. long. 



Corolla-tube 8-10 mm. long; hypanthium sparsely puberulent. 

 Corolla-tube 6 mm. long; hypanthium densely puberulent. 



10. E. lineatum. 



11. E. subcor datum. 



12. E. triflorum. 



13. E. rupicola. 



14. E. brachycarpum. 



15. E. floribundum. 



16. E. rotundatum. 



17. E. ellipticum. 



18. E. myrtifolium. 



19. E. elegans. 



20. E. parvifLorum. 



21. E. crassifolium. 



22. E. Shaferi. 



23. E. velutinum. 



24. E. barbatum. 



25. E. mexicanum. 



26. E. indulum. 



1. Exostema Coulteri Hook, f.; Hemsl. Diag. PI. Nov. 32. 1879. 



Shrub, glabrous throughout, the branches slender, densely leafy; stipules subulate, de- 

 ciduous; petioles slender, about 6 mm. long; leaf- blades ovate-oblong, 5-6.2 cm. long, cuneate 

 at the base, acuminate at the apex with an acutish acumen, coriaceous; inflorescence terminal, 

 cymose-corymbose, few-flowered, the pedicels very short; calyx-lobes subulate; corolla sub- 

 cylindric, 1.2-1.6 cm. long, the lobes very short, rounded, erect or ascending; stamens included; 

 capsule oblong, 4-6 mm. long. (Description compiled.) 



Type locality: Zimapan, Hidalgo. 

 Distribution: Known only from the type locality. 



2. Exostema spinosum (Le Vavass.) Krug & Urban; Urban, Ber. 

 Deuts. Bot. Ges. 15: 262. 1897. 



Cinchona spinosa Le Vavass. Obs. Phys. 37: 243. 1790. 

 Calesbaea Vavassorii Spreng. Syst. 1: 416. 1825. 

 Catesbaea elliptica Spreng.; DC. Prodr. 4: 401, as synonym. 1830. 

 Exostema Vavassorii Griseb. Cat. PI. Cub. 126. 1866. 



Shrub, 1-2 meters high, much branched, the branches stout, rigid, grayish, the branchlets 



slender, rigid, spinose, minutely puberulent or hirtellous when young; stipules minute, deltoid, 



acute, brownish; petioles 1 mm. long or shorter; leaf- blades oval or oblong, 3-8 mm. long, 



1.5-4 mm. wide, rounded or obtuse at the base, broadly rounded at the apex, thick-coriaceous, 



lustrous above, the costa evident beneath, the lateral veins obsolete, the margin often sub- 



revolute; flowers axillary, solitary, the pedicels very slender, 5-7 mm. long, the bractlets 



