110 
IOWA ACADEMY OP SCIENCES. 
into a groove in the lower lip of the corolla. This mechanism 
may thus assist the anthers to return to their normal position, 
or may prevent the proboscis of the insect from being thrust 
down the side of the corolla, and thus evading the pollen. 
Many small bees were seen to visit these flowers on bright 
days. The plant blossoms during July and August and a few 
flowers were found in the latter part of September. 
NOTES OF SOME INTRODUCED PLANTS OF IOWA. 
L. H. PAMMEL. 
Since the settlement of Iowa many changes have taken place 
in our flora, especially with reference to introduced plants, and 
the disappearance of many indigenous species owing to break- 
ing up of prairies, and the destruction of some timber areas, 
and the draining of ponds and lakes. 
It is with difficulty that species of Potamogeton have been 
enabled to retain their hold in water, or that Gypripedium 
spectabile should maintain itself in the wooded and much pas- 
tured timbers of Iowa. With the early settlement of Iowa 
there came a host of European weeds. They are so well 
naturalized that it is no longer possible to state whether they 
are introduced or indigenous, nor are we able to state when 
they were introduced. In fact there are no early collections, 
and in many cases early collectors failed to note whether the 
plant was introduced or indigenous. We have no early records 
for such common weeds as Portulaca oleracea^ Verbascum thap- 
sus, Anthemis cotula, Malva rotundifolia, Ghenopodium album. 
Indeed, we are unable to say how rapidly these weeds have 
spread. In fact when we look over our introduced plants we 
find that there are but few cases in which there are statistical 
records such as we now have for Lactuca scariola, Salsola kali, 
var. tragus or Solarium rostratum, Eieracum aurantiacum and a 
few others. Those who are connected with our experiment 
station have frequent requests to identify weeds, and it would 
