20 FLORA OF THE YELLOWSTONE NATIONAL PARK. 



L., and Polygonum aviphibium, 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 Subular-ia aquatica, L. ; Elatine triandra^ 

 Schkuhr. ; Ii<oetes Bolanderi, Engelm., and Callitriche autum- 

 nalis^ L. Floating on the surface are Ranunculus muUifidus, 

 Pursh. ; Polygonum amj)hibium^ 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 Cali/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 floi'a in many respects 

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

 (*) have not been observed, with a very few exce])tions, 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 herhacea^ 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. Tlie most characteristic species are Ghrysopsis villosa, 

 Nutt.; Gnaphalium Sprengeln^Jlooli and Arn.; Triglochin mari- 

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

 The latter frequently covers the ground with* a deuse velvet 

 carpet, glistening with crystal drops of condensed steam. Ruppia 

 maritima has been observed in situations where the water had a 

 temperature of 90° Pahr. The small streams are filled with 

 Potamogeton pectinatus, L., and frequently with vast quantities 

 of Lemna. 



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



