586 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 
9. LEIOSTEMON Raf. 
Slender, much branched perennial herbs, about 80 cm. high or less, with narrow 
leaves and showy paniculate flowers; corolla hardly bilabiate, obliquely salverform, 
white or tinged with red outside; fifth stamen glabrous, occasionally with a rudimentary 
anther. 
KEY TO THE SPECIES. 
Tube of corolla 10 to 15 mm. long; throat little dilated........... ... 1. L. ambiguus. 
Tube of corolla 5 mm, long or less; throat much dilated.............. 2. L. thurberi. 
1. Leiostemon ambiguus (Torr.) Greene, Leaflets 1: 223. 1906. 
Pentstemon ambiguus Torr, Ann, Lyc. N. Y. 2: 228. 1828. 
Leiostemon purpureus Raf. Atl. Journ, 145, 1833. 
TypE Locauity: ‘Near the Rocky Mountains,’’ Colorado or New Mexico. 
Rance; Utah and Colorado to western Texas and southern California, 
New Mexico: Clayton; Nara Visa; Albuquerque; Aden; Hop Canyon; Jarilla; 
south of Melrose; Buchanan. Dry hills and plains, in the Lower and Upper Sonoran 
zones. 
2. Leiostemon thurberi (Torr.) Greene, Leaflets 1: 223. 1906. 
Pentstemon thurberi Torr. U.S. Rep. Expl. Miss. Pacif. 7: 15. 1857. 
Pentstemon ambiguus thurberi A. Gray, Proc. Amer. Acad. 6: 64. 1862. 
TyPE LocaLity: Burro Mountains, New Mexico. Type collected by Antisell in 
August, 1854. 
Rance: New Mexico and Arizona to northern Mexico. 
New Mexico: Magdalena Mountains; Albuquerque; near Juniper Spring; Carrizozo; 
Gage. Dry hills and plains, in the Lower and Upper Sonoran zones. 
10. GRATIOLA L. HeEpGE uyssop. 
Low annual, 30 cm. high or mostly less, with narrow sessile leaves and small axillary 
flowers on peduncles nearly equaling the leaves; calyx lobes nearly equal; corolla 
deeply bilabiate, the upper lip entire or 2-cleft, the lower 3-cleft; capsules 4-valved, 
many-seeded. 
1. Gratiola virginiana L. Sp. Pl. 17. 1753. 
TyPE Loca.ity: ‘‘ Habitat in Virginia.’’ 
RanGe: British America to California and Florida, 
New Mexico: Chama (Standley 6659); Brazos Canyon (Standley 4: Bollman). 
Wet ground, in the Transition Zone. 
11. MIMULUS L. Monkey Fiower. 
Annual or perennial herbs, usually growing in wet soil, 50 cm. high or less, with 
solitary, axillary, or by the reduction of the leaves racemose flowers; sepals united 
into a 5-angled tube with short oblique limb; corolla strongly 2-lipped, yellow or 
purple, the upper lip spreading or reflexed, the lower erect; stamens 4; capsules 
loculicidally dehiscent, inclosed in the persistent papery calyx. 
KEY TO THE SPECIES. 
Corolla purple or reddish. 
Corolla 8 mm. long or less; annual......................2..--- 1. M. rubellus. 
Corolla 35 mm. long or more; perennial....................--- 8. M. cardinalis. 
Corolla yellow. 
Corolla tube twice as long as the calyx....................... 2. M. parvulus. 
Corolla tube little or not at all exceeding the calyx, 
Calyx teeth equal; leaves elliptic or narrowly oblong. ..... 3. M. gratioloides. 
