@iumore] INFLUENCE OF POPULATION ON FLORA 59 
here by immigrants from those States; other species, for instance 
Salsola pestifer (Russian thistle), have been introduced directly from 
Europe. 
Verbascum thapsus (mullein), Aretiwm minus (burdock), Leon- 
todon taraxacum (dandelion), and many other weeds now very com- 
mon, are of recent introduction by this means, besides many plants 
purposely introduced by the white settlers, such as Vepeta cataria 
(catnip), Roripa armoracia (horseradish), and other herbaceous 
plants, and fruit and timber trees, vines, and shrubs. 
Although these sources of plant immigration into Nebraska are 
recognized, the human factor in plant distribution prior to the 
European advent is not so obvious and may not have suggested itself 
to most of my readers. But the people of the resident tribes traveled 
extensively and received visitors from distant tribes. Their wants 
required for various purposes a great number of species of plants 
from mountain and plain and valley, from prairie and from wood- 
land, from regions as remote from each other as the Rio Grande and 
the Great Lakes and St. Lawrence. 
Their cultivated plants were all probably of Mexican origin, com- 
prised in the Cucurbitaceae (squashes, pumpkins, gourds, and water- 
melons), Phaseolus vulgaris (garden bean) in 15 or more varieties, 
Zea mays (corn) in five general types aggregating from 15 to 20 
varieties, and their tobacco, Vicotiana quadrivalvis. 
But besides these known plant immigrants already carried into Ne- 
braska by human agency before the advent of Europeans, certain facts 
lead me to believe that some plants not under cultivation, at least in 
the ordinary sense, owe their presence here to human transporta- 
tion, either designed or undesigned. Parts of certain plants, and in 
most cases the fruits or fruiting parts, were desired and used for their 
fragrance, as the seeds of Aguilegia canadensis, the fruiting tops of 
Thalictrum purpurascens, the entire plant of Galium triflorum, the 
fruits of Zanthoxylum americanum, and leaves and tops of Monarda 
jistulosa. Any of these easily might be, and probably were, unde- 
signedly distributed by the movements of persons carrying them. 
Desirable fruits were likely carried from camp to camp and their 
seeds dropped in a viable condition often in places favorable to their 
growth. Malus ioensis is found in Iowa and on the west side of the 
Missouri River in the southeast part of Nebraska, but nowhere higher 
up the Missouri on the west side except on a certain creek flowing 
into the Niobrara from the south near the line between Knox County 
and Holt County. The Omaha and Ponea call this creek Apple 
Creek on that account. The original seed, so far from their kind, 
probably reached this place in camp kitchen refuse. 
