37 



rticate at least that long a time since the pericd began. 



The almost universal distribution of Middle Temperate species 

 as a whole could be largely accounted for by bird migration and wind 

 (1 stribution because almost every mountain range has a larger or 

 smaller area of this flora along its flanks and the ranges are for the 

 most part west of the Wasatch about twenty miles apan., and for 

 the most part parallel north and south, while the great Uintah 

 .c..ige ends on to 'the Wasatch like the shank of the letter "T." But 

 vvben v.e come tO' study the species by groups we find they clearly 

 show origin by difforentiation of primai'y forms. The present distri- 

 bution is also a matter of water transportation by means of the great 

 lakes Lahontan, Bonneville, and Columbia. The similarity of forms 

 of the Wasatch to those of the east base of the Sierras on the old 

 shore lines is noticeable, as is that of the Bitterroot and Flathead 

 region of western Montana to the east base of the Cascades. A. Utah- 

 ensis occurs along the old shore lines in the Sierras and Wasatch, 

 and A. Gibbsii and collinus have similar distribution in the Flathead- 

 Cascade regions. This similarity is still more noticeable in other 

 genera such as Allium and Lupinus. 



From geological evidence we know that the Middle Temperate 

 climate persisted a long time in the West, and was displaced only 

 by the drying up of the lakes. Then it migrated a little farther north 

 after abandoning the floor of the basins and invading parts of Wyo- 

 ming, Idaho and Montana, and extended to the Saskatchewan on the 

 the Plains. For the same reason it ascended toward the tops of the 

 higher ranges of Arizona and Mexican regions. It still persisted in 

 the Sandias, Mogollons, Catalinas, Santa Ritas and Huachucas, and 

 even covered the tops of the Sierra Madres of Chihuahua and formed 

 broad belts on the Volcanoes of central Mexico. 



In the eastern and Atlantic regions the only representatives of 

 the Middle Temperate are the Uliginosi and a very few Argophylli and 

 Sarcocarpi. The Plains region has A. montanus, triphyllus, lotiflorua, 

 crassicarpus, Missouriensis, Plattensis and moUissimus. The Colo- 

 rado-New Mexican region in the mountains has of the Homalobi such 

 species as campestris, junceus, montanus, tenellus, simplicifolius in 

 the north and humistratus and humillimus at the south. Of the Deb- 

 iles A. leptaleus and debilis are in the mountain meadows and ex- 

 tending over to the west, and sparsiflorus in the Colorado^ region. 

 Of other groups A. aboriginum and andinus are in the mountains loti- 

 florus and pectinatus on the Plains, megacerpus in the western moun- 

 tains, nitidus on the Plains, agrestis in cold meadows, parviflorus 

 O'n the plains, Flexuosi there also and in the foothills with gracilen- 

 tus at the south, Misso'uriensis and Platettensis are on the Plains, and 

 Parryanus and Shortianus in the foothills with Feensis at the 

 Bouth. The Uliginosi are cosmopolitan. 



Tile Montana-idaho-Wyoming-Britisli American region has a good 

 assortment of Homalobi as was to be expected, those already named 

 including A. sericoleucus: It also has the Triphylli and Debiles: the 

 Inflati have pauciflorus and miser; the Alpini. A. aboriginum and an- 

 dinus. A. lotiflorus is on the Plains. A. pectinatus and Grayi repre- 

 sent the Podo-sclerocarpi. The Uliginosi have A. Canadensis, termina- 

 lis and Oreganus. The Hypolottides are there. A. flexuosus is there. 

 The Argophylli have cibarius, inflexus, Missouriensis and argophyllua. 

 A. crassicarpus represents the Crassicarpi. There is A. bisulcatus. 

 The Galegiformes have Drummondii and racemosus. 



The Columbia Basin region has the usual Homalobi and steno- 

 phyllus: the Debiles have Bourgovii, debilis and leptaleus; the Inflati 

 have besides those named A. Craigi, diurnus and lentiginosus. There 

 are the usual Alpini. There are the Collini. There is A. Beckwithii. 

 accidens and Alvordensis. There are the Reventi-Arrecti] There 



