THE GENUS LEIOSTEMON. 223 
T. OBSCURA. Ptelea obscura, Greene, l. c. Pericarp large, 
subquadrate-oval, its margin obtuse. 
Interior of northern L. Calif., near Santo Tomas. 
T. NUCIFERA. Ptelea nucifera, Greene, l. c. Fruit large, 
oval, sharply carinate all around the margin. 
Near a desert water hole, middle of L. Calif., inland. 
\ 
The Genus Leiostemon. 
When nearly thirty years since in New Mexico I for the first 
time saw the type of this genus, not knowing its name, I 
regarded it as possibly a Gerardia, never thinking of Peniste- 
mon at all in connection with it, so far removed as it is in habit 
and in the structure of its flower from the last named. I was 
therefore not well satisfied when I learned that its only name in 
botany was Pentstemon ambiguus; the trivial name also telling the 
tale of Torrey’s own doubt about the reasonableness of the 
placing of it as a species of Pentstemon. 
Within the last year, having been led to examine and com- 
pare a series of specimens from different places, I reached the 
decision that the type ought to be excluded from Penistemon and 
given the rank of a genus. I could“not readily invent a pleasing 
generic name for it, and the subject passed out of my mind. 
This may have been fortunate; for, in reading lately some 
botanical articles by Rafinesque in the Atlantic Journal, I came 
upon his establishment of this type in-the rank it demands, and 
with a name that may easily pass without any objection that I 
can see. 
The species of LE1osTEMON seem to me to be two at the least, 
with possibly as many more. 
L. AMBIGUUS. Pentstemon ambiguus, Torr. L. purpureus, 
Raf. - 
L. THurBERI. Pentstemon Thurberi. Torr, 
