STANDLEY TREES AND SHRUBS OF MEXICO. 839 



Flowers axillary or lateral ; sepals imbricate. 



Disk of the flower without staminodia-like appendages. 



Plants armed with spines; stamens hypogynous, the filaments free or 



nearly so 7. MYROXYLON. 



Plants unarmed ; stamens perigynous, the filaments united to form a tube. 



8. SAMYDA. 

 Disk with staminodia-like appendages. 



Style none; stamens 30 or more 9. ZUELANIA. 



Style evident; stamens 6 to 22 10. CASEARIA. 



1. HOMALIUM Jacq. Enum. PI. Carib. 5. 1760. 

 Reference : Blake, The genus Homalium in America, Contr. U. S. Nat. Herb. 



20: 221-235. 1919. 



Shrubs or trees ; leaves short-petiolate, crenate, coriaceous ; flowers in axil- 

 lary spikes or racemes ; calyx tube turbinate, connate with base of ovary, the 

 limb 6 or 7-lobate; petals 6 or 7, linear-oblong, persistent; stamens in fascicles 

 opposite the petals ; fruit a capsule, 2 to 5-valvate at apex. 



Leaves pilosulous beneath over the whole surface 1. H. mollicellum. 



Leaves barbate beneath along the costa, otherwise glabrous. 



2. H. trichostemon. 



1. Homalium mollicellum Blake, Contr. U. S. Nat. Herb. 20: 226. 1919. 

 Known only from the type locality, Coquillo, Guerrero. 



Leaves elliptic or oblong-elliptic, 5.5 to 9.5 cm. long, short-pointed, rounded at 

 base, crenate, puberulous above ; racemes 7 to 9.5 cm. long ; calyx tomentulose ; 

 corolla in fruit 12 mm. wide ; stamens 4 to 7 in a fascicle, the filaments pilose. 



2. Homalium trichostemon Blake, Contr. Gray Herb. n. ser, 53: 60. 1918. 

 Michoaccin to Oaxaca ; type from Cafetal Montecristo, Pochutla, Oaxaca, 



altitude 800 meters. 



Tree, 12 meters high ; leaves elliptic or oval, 6 to 11.5 cm. long, obtuse or 

 acute, cuneate or rounded at base, crenate-serrate ; racemes 6 to 7 cm. long ; calyx 

 grayish-puberulous ; corolla 11 to 13 mm. wide ; stamens in fascicles of 5 to 7, 

 the filaments pilose. "Palo de piedra " (Oaxaca). 



DOUBTFUL SPECIES. 

 Homalium senarium Moc. & Sesse; DC. Prodr. 2: 54. 1825. Described from 

 Mexico ; probably the oldest name for H. trichostemon. 



2. ONCOBA Forsk. Fl. Aegypt. Arab. 103. 1775. 



1. Oncoba laurina (Presl) Warb. in Engl. & Prantl, Pflanzenfam. 3'": 19. 1894. 



Lindackeria laurina Presl, Rel. Haenk. 2: 89. fl. 65. 1836. 



Mayna laurina Benth. Journ. Linn. Soc. Bot. 5: Suppl. 81. 1861. 



Originally described from western Mexico, but not since collected there ; 

 it is not improbable that the type came from Panama. Costa Rica, Panama, 

 and Colombia. 



Tree, 12 to 15 meters high, the trunk 30 to 35 cm. in diameter, the crown 

 pyramidal ; bark gray ; leaves long-petiolate, lance-oblong or ovate-oblong, 

 12 to 30 cm. long, cuspidate-acuminate, entire, glabrous or nearly so ; in- 

 florescence terminal, racemose-paniculate ; sepals 5, 7 mm. long ; petals 5, 

 1 cm. long, white ; stamens numerous ; fruit globose, about 1 cm. in diameter, 

 covered with long spinelike bristles, tardily dehiscent ; seeds 1 to 4. 



3. BANARA Aubl. PI. Guian. 1 : 547. 1775. 

 1. Banara dioica Benth. Journ. Linn. Soc. Bot. 5: Suppl. 94. 1862. 



Veracruz. 



Leaves elliptic-oblong or lanceolate, 5 to 7.5 cm. long, acuminate, remotely 

 dentate, 3-nerved, subcorlaceous, glabrous or beneath pubescent ; flowers dioe- 



