290 NORTH AMERICAN FLORA [Volume 25 



inequilateral at the base. Flowers perfect, in axillary or subterminal panicles. Calyx small, 

 5-lobed (rarely 4-lobed), the lobes imbricate. Petals 5 (rarely 4), free, contorted, spreading. 

 Staminal tube urn-shaped, or cylindric-urn-shaped, 10-toothed. Anthers 10, inserted below 

 the sinuses of the staminal tube, included. Disk saucer-shaped or shallowly cup-shaped, fluted 

 on the outside, the margin crenate. Ovary 5-celled (occasionally 4-celled), sessile in the disk; 

 style columnar; stigma discoid. Ovules numerous in each cavity, pendulous. Fruit a large 

 5-celled (occasionally 4-celled), 5-valved (occasionally 4-valved) woody capsule usually sep- 

 ticidally dehiscent from the base, the valves in two layers, separating from a persistent 

 5-winged (rarely 4-winged) axis which is thickened toward the apex and conspicuously scarred 

 at the point of attachment of the seeds in two rows along the edges of each face. Seeds 10-14 

 in each cavity, samaroid, imbricated downward in 2 rows in each cavity, expanded into a long 

 chartaceous wing above; endosperm thin, fleshy; embryo transverse, with large closely united 

 cotyledons; radicle short. 



Type species, Swielenia Mahagoni Jacq. 



Leaflets sessile or subsessile, usually tapering to a very long, slender acuminate 



tip. 

 Leaflets narrowly lanceolate or lanceolate, 6-10 cm. long, 1.5-2.5 cm. broad; 



flowering inflorescence about 6 or 8 cm. long, the branches short; seeds 



light-brown. 1. 5. humilis. 



Leaflets obliquely-ovate or elliptic-ovate, 8.4—14 cm. long, 3-5 cm. broad; 



flowering inflorescence 2 dm. or more long, the slender branches long and 



spreading; seeds reddish-brown. 2. 5. cirrhala. 



Leaflets usually distinctly petioluled; acute to acuminate at the apex. 



Leaflets 7.5-15 cm. long, 2.5-7 cm. broad; capsule 12-15 cm. long, 7-7.5 



cm. broad. 3. 5. macrophylla. 



Leaflets 2.5-7 cm. long, 1.3-3.5 cm. broad; capsule 6-10 cm. long, 4—6 cm. 



broad. 4. S. Mahagoni. 



1. Swietenia humilis Zucc. Abh. Akad. 

 Munch. 2: 355. 1837. 



A tree 6-10 m. tall; leaves 8-21 cm. long; leaflets narrowly lanceolate to lanceolate, 6-10 

 cm. long, 1.5-2.5 cm. broad, more or less oblique, tapering at the apex into a long slender acu- 

 minatum, acute at the base, sessile or subsessile, reticulate- veined, entire, coriaceous, glabrous; 

 panicles 5-7 cm. long; calyx 2.5 mm. broad, the lobes broadly rounded-ovate, acute at the 

 apex, minutely denticulate; corolla 10-1 1 mm. broad; petals obovate, 5-6 mm. long, 2.5-3 mm. 

 broad; teeth of the staminal tube acute above the middle; ovary turbinate, immersed for 

 nearly half its length in the shallow cup-shaped disk; capsule umbonate, 15-20 cm. long, 10-12 

 cm. thick; seeds 6-8 cm. long, light-brown. 



Type locality: On the Pacific coast, in dry rocky places, scarcely 300 meters above the sea> 

 especially near Tehuantepec. 



Distribution: Mexico and Central America. . 



Illustrations: Abh. Akad. Munch. 2: pi. 7, A, B; Schnizl. Ic. pi. 226, f. 18-23. 



2. Swietenia cirrhata Blake, Jour. Wash. 

 Acad. 10: 292. 1920. 



A tree with grayish-brown twigs; leaves 1.5-3 dm. long; leaflets 6-12, obliquely ovate 

 or elliptic-ovate, 8.5-14 cm. long, 3-5 cm. broad, acuminate, tipped by a filiform twisted cusp 

 3-13 mm. long, strongly inequilateral and acute or rounded at the base, subsessile, reticulate- 

 veined, entire, subcoriaceous; panicles 20 cm. or more long, the branches slender, spreading; 

 pedicels 1.5-2 mm. long; calyx 0.8-1 mm. long, 5-lobed, the lobes broadly deltoid or suborbic- 

 ular, rounded, ciliolate; petals oblong-oval or oblong obovate, 4.6 mm. long, 2.5-2.8 mm. 

 broad; staminal tube glabrous, 3.5 mm. long, the teeth triangular-ovate, acutish; ovary 

 broadly ellipsoid, glabrous, sessile in the disk; seeds light-brown. 



Type locality: La Salada. Michoacan. 

 Distribution: Mexico. 



