1352 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM 



2. HOUSTONIA L. Sp. PI. 101. 1753. 

 Reference: Standley, N. Amer. Fl. 32: 24-38. 1918. 



Small shrubs or usually herbs; leaves small; flowers small, axillary or in 

 dichotomous cymes; caly.x lobes 4; corolla funnelform or salverform, the limb 

 4-lobate, the lobes valvate; fruit a small 2-celled capsule, loculicidally dehiscent; 

 seeds not winged. 



Several herbaceous species occur in Mexico. 



Capsule less than half inferior 1. H. fasciculata. 



Capsule more than half inferior. 



Branches glabrous 2. H. mucronata. 



Branches hirtellous or scabrous. 



Flowers in cymes; leaves not acerose; corolla tube minutely hirtellous out- 

 side 3. H. peninsularis. 



Flowers mostly solitary; leaves acerose; corolla tube glabrous. 



Leaves mostly verticillate; flowers sessile or nearly so 4. H. acerosa. 



Leaves opposite; flowers mostly pedicellate 5. H. polypremoides. 



1. Houstonia fasciculata A. Gray, Proc. Amer. Acad. 17: 203. 1882. 

 Chihuahua and Coahuila. Western Texas and southern New Mexico; type 



from Presidio, Texas. 



Shrub, 40 cm. high or less, the branches scaberulous or hirtellous; leaves oppo- 

 site or verticillate, linear, 3 to 10 mm. long, scaberulous or glabrate; flowers in 

 small cymes; corolla white, 3 to 4 mm. long. 



2. Houstonia raucronata (Benth.) Robinson, Proc. Amer. Acad. 45: 401. 1910. 

 Hedijotis mucronata Benth. Bot. Voy. Sulph. 19. 1844. 



Houstonia fruticosa Rose, Contr. U. S. Nat. Herb. 1: 132. 1892. 

 Southern Baja California; type from Magdalena Bay. 



Glabrous shrub, 60 cm. high or less; leaves linear, 3 to 18 mm. long; flowers 

 in small terminal cymes; corolla 10 to 12 mm. long, white. 



3. Houstonia peninsularis T. S. Brandeg. Zoe 5: 160. 1903. 

 Baja California; type from Sierra de la Trinidad. 



Shrub, 30 cm. high or less; leaves linear, 1 to 4 cm. long, hirtellous; corolla 

 purple, 15 mm. long. 



4. Houstonia acerosa A Gray; Benth. & Hook. Gen. PL 2: 60. 1873. 

 Hedyotis acerosa A. Gray, PI. Wright. 1: 81. 1852. 



Mallostoma acerosum Hemsl. Biol. Centr. Amer. Bot. 2: 31. 1881. 

 Coahuila, Nuevo Le6n, and San Luis Potosf. Western Texas. 

 Plants fruticose or suffrutescent, 30 cm. high or less; leaves 5 to 12 mm. long, 

 rigid, scaberulous or hirtellous; corolla 12 to 16 mm. long. 



5. Houstonia polypremoides A Gray, Proc. Acad. Amer. 21: 379. 1886. 

 Chihuahua; type from Santa Eulalia Mountains. Western Texas and southern 



New Mexico. 



Shrub, 20 cm. high or less; leaves rigid, 5 to 12 mm. long, scaberulous or hirtel- 

 lous; corolla white, 8 to 11 mm. long. 



3. BACHICALLIS DC. Prodr. 4: 433. 1830. 



A single species is known. 

 1. Rachicallis americana (Jacq.) Hitchc. Rep. Mo. Bot. Gard. 4: 92. 1893. 



Hedyotis americana Jacq. Enum. PL Carib. 12. 1760. 



Yucatdn, on coastal rocks. West Indies; type from Cuba. 



Erect or procumbent shrub, 2 meters high or less; leaves linear-oblong to 

 obovate, 2 to 8 mm. long, obtuse or acute, coriaceous; flowers yellow, solitary, 

 sessile in the leaf axils; corolla salverform, 8 to 10 mm. long, sericeous, the limb 

 4-lobate; capsule 3 mm. long, septicidally bi valvate, many-seeded. 



