536 PirpeER: West AMERICAN 
the Gray herbarium, of that in the California Academy of Science, 
and of that in the herbaria of Mr. W. C. Cusick and Professor L. 
F. Henderson, together with my own. Besides the species here 
considered there are several more undoubtedly distinct species 
‘represented in the Gray herbarium, which owing to incomplete 
material it was not deemed wise to describe. It is very desirable 
in the future that collectors endeavor to secure both flowering and 
fruiting specimens of each species. The great bulk of the mate- 
rial in herbaria is either in flower or in fruit, so that it is often bid 
difficult to determine which goes with which. Belated flowers m 
fruiting material are unsatisfactory, as they are frequently much 
smaller than is typical and therefore apt to be misleading. 
So far as my experience goes in the field, the color of the 
flowers, contrary to what might be expected, is very constant. 
‘While white-flowered specimens are notoriously common in blues, 
flowered plants, the present genus seems to be exceptional in this 
respect. Pile 
Owing to the great confusion of material in herbaria, a full list 
of the specimens examined is given under each species. 
Key to the Species 
Biennials or perennials; nutlets armed on the margins with free or 
subulate glochidiate prickles. ‘ : free 
I. Back of nutlets unarmed or with short glochidiate prickles ; marginal prickles 
to the base or nearly so. 
Corolla appendages smooth or merely papillate. uke 
Appendages broader than long: protuberance short, broad : flowers 
united flat 
‘bunda. 
Flowers small, 4-6 mm. broad. 1. LZ. pe oy 
Flowers larger, 8-10 mm. broad. 2. - Set 
Appendages as long as broad: the oblong protuberance scarcely P 
flowers white. 
Foliage rather softly pubescent. 
Foliage harshly papillose-scabrous. 
4: Ze Henderson. 
4: Pe trachyphylla- 
Corolla appendages pubescent. ] 
das long, 
Flowers small, less than 5 mm. broad; appendage about as ser netorum 
short-pilose, the protuberance very small. 5. LP 
Flowers larger, 5-12 mm. broad. 
Appendage short-pilose. sea except 
Flowers white : pubescence rather harsh, mostly appres 
on the lower part of the stem and the Se yer 
atilis. 
Flowers blue: pubescence soft, not appressed. 7- pee . 
Flowers blue: pubescence smooth, very closely hae " cosiihie 
few bristles on the lower petioles. : 
