37 
Gicate 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 
distribution 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 apai, and for 
the most part parallel north and south, while the great Uintah 
rauge ends on to the Wasatch like the shank of the letter “T.” But 
when we come to study the species by groups we find they clearly 
show origin by differentiation of primary 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, lotiflorus, 
crassicarpus, Missouriensis, Plattensis and mollissimus. 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 Joti- 
florus and pectinatus on the Plains, megacerpus in the western moun- 
tains, nitidus on the Plains, agrestis in cold meadows, parviflorus 
on the plains, Flexuosi there also and in the foothills with gracilen- 
tus at the south, Missouriensis and Platettensis are on the Plains, and 
Parryanus and Shortianus in the foothills with Feensis at the 
south, The Uliginosi are cosmopolitan. 
The Montana-Idaho-Wyoming-British 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 argophyllus. 
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-Arrectii There 
