20 FLORA OF THE YELLOWSTONE NATIONAL PARK. 



L., and Polygonum amphibium, L. At the outlet of Yellowstone 

 Lake is a small pond a few feet in depth and several acres in 

 extent, which is remarkable for containing a great number of 

 the rare and local species of the region. On the bottom and 

 submerged grow Subularia aquatica, L. ; Elatine triandra, 

 Schkuhr. ; Isoetes Bolanderi, Engelm., and Callitriche autum- 

 nalis, L. Floating on the surface are Ranunculus multlfidua, 

 . Pursh. ; Polygonum amphibium, L. ; Sagittaria, Sparganium, 

 several Lemnas and Potamogetons. In the mud at the water's 

 edge were collected Elatine Americana, Arn. ; Tillsea angusti- 

 folia, Nutt. ; Krynitzkia Calif ornica, Gray, and Limosella 

 aquatica, L. 



FLORA OF THE HOT SPRINGS AND GEYSER AREAS. 



The alkaline nature of the soil and artificial warmth of the 

 hot spring and geyser areas have created a flora in many respects 

 peculiar to itself. In the list given below those species marked 

 (*) have not been observed, with a very few exceptions, on other 

 than hot spring soil. It will be seen that there are a number 

 normal on our sea coasts, and more or less in saline situations 

 in the interior, such as Salicorma herbacea, L.; Rumex maritimus, 

 L., and Triglochin maritimum, L., and others which belong to 

 the flora of a lower and more arid region. The bleak formations 

 proper support but a scanty vegetation, but where overlaid with 

 soil on its borders, and around less active rents, and especially 

 along the hot streams, there will be found a most luxuriant vege- 

 tation. The most characteristic species are Chrysopsis villosa, 

 Nutt.; Gnaphalium Sprengelii, Hook and Arn.; Triglochin mari- 

 timum, L., and a grass Panicum dichotomum, L., var. pubescens. 

 The latter frequently covers the ground with a dense velvet 

 carpet, glistening with crystal drops of condensed steam. Ruppia 

 maritima has been observed in situations where the water had a 

 temperature of 90 Fahr. The small streams are filled with 

 Potamogeton pectinatus, L., and frequently with vast quantities 

 of Lemna. 



Botrychium ternatum, Swartz, var. australe, Eaton, has never 



