ENTOMOLOGIST AND BOTANIST. 



S43 



means not beyond the limits of scientific expla- 

 nation. Granted this, and we see in these 

 strangely placed plants the lineal descendants 

 of maritime races, inhabiting the coast of a sea 

 once stretching from the lakes to the Atlantic, 

 and adapted, by degrees, to the conditions of a 

 lite beside fresh waters. 



An interesting natural feature supporting our 

 hypothesis of an extensive ocean, embracing 

 the Great Lake^, is found near the city, in the 

 terrace elevated some twenty-five feet above 

 the present level of Lake Michigan, and extend- 

 ing, I am told, for many miles, forming, evi- 

 dently, the ancient lake boundary. This is pe- 

 culiarly apparent in the neighborhood of Calu- 

 met lake, which, without doubt, once formed 

 part of Lake Michigan. The terrace here is 

 about a mile distant from Calumet lake, and 

 standing upon it and looking down upon tlie 

 flat lands below, as the eye follows the curve of 

 the high land, the basin-like form strikes the 

 eye with conviction, and one instinctively gr.asps 

 the conclusion that here, in the remote past, 

 was the shore of Lake Michigan, which, in its 

 retrogression, left this noble terrace and Calu- 

 met lake as mementoes of the day of its wider 

 sweep and oceanic proportions. 



Viewing this terrace botanically also, we find 

 new confirmation of our theory. One is struck 

 immediately by its older aspect compared witli 

 the low grounds between it and the lake. 

 While these have the marked indications of 

 comparative newness and of submersion beneath 

 the waters, the terrace lands, in soil and vege- 

 table growth, suggest the idea of immemorial 

 highlands; and a close examination of the plants 

 supports the first impression. The change in 

 ■ the flora of the neighborhood, within the space 

 of a few rods, as one walks up the terrace from 

 the low grounds to the wood lands above, is 

 actually startling. Beside the noble tree growth 

 we find a multitude of i^lants suggesting the 

 Eastern States. Comptonia asplenifolia, the 

 blue-berry, the ferns Osmunda regalis a,\\d Clay- 

 tonia, Honsionia purpurea, the orchids, Habe- 

 naria tridentata and lacera, with that curious 

 plant, rare anywhere except the sea coast, Xyris 

 flexuosa, and everywhere one treads on the soft 

 mosses of Eastern woods." 



Let us repeat these inquiries : Are these 

 plants the remains of an ancient maratime vege- 

 tation ? or have they been brought hero by the 

 general agencies of plant distribution, and 

 found conditions of soil, humidity of atmo — 

 phere (modified by the existing large bodies of 

 water), etc., favorable for their growth, the 

 presence of salt water not being one of those 

 conditions? 



Let us add another: May these species be of 

 a cosmopolitan character spreading over vast 

 areas, and accommodating themselves to a great 

 variety of circumstances? 



In determining these questions it is necessary 

 to take a somewhat enlarged view of the geo- 

 graphical range of the species which have been 

 referred to, and of such others as may throw 

 light on the subject. 



Thus, the Baltic Rush OJuncus Balticus) fol- 

 lows the course of the Lakes from the St. Law- 

 rence to Chicago, reappears on the Western 

 rivers, extends into the Rocky Mountains, and 

 thence to the Pacific coast from California to 

 Alaska. 



The Arrow-grass ( Triglochin maritlmum) 

 has quite as extended a range, occurring in the 

 prairie marshes or bogs, reappearing in the 

 Rocky Mountains on muddy banks of the Grand 

 and Green rivers, and again on the Pacific. 



Almost the same may be said of the Squirrel 

 tail grass (Hordeiim j iibatiim) , although its se- 

 lection of soil is difTerent. 



The seaside Crowfoot {Rnnunculus cymbala- 

 rius) appears again on the sandy borders of the 

 Platte in Colorado, and also on the west side of 

 the Mountains. Artemesia cauduta and Atri- 

 plex hastata may be named in the same con- 

 nection. 



We have not observed Bumex maritiimis in 

 the immediate vicinity of the Great Lakes, but 

 it is found on marshy prairies thirty or forty 

 miles back from the Lake, also in Missouri, and 

 again on the borders of ponds and rivers west 

 of the Rocky mountains. The Willow dock 

 {Rumex salicifoUus) of the coast of Massachu- 

 setts and Maine, also grows on western river 

 banks, as at Omalia, aud west of the mountains 

 in Middle Park, and again on the Pacific. One 

 of the peculiar plants of the lake-border which 

 we have mentioned {Corispermum hyssopifo- 

 lium) does not occur on the Atlantic, but is 

 found on our North-western coast iu Alaska, 

 and on sandy river banks in the interior basins. 



Indeed, on the Great Plains, and iu the basins 

 wests of the mountains, there are still other 

 plants which are usually regarded as maritime, 

 for instance, Olaux maritinia, Chenopodina 

 maritivia, and Sesuvium Fortulacastrum; also 

 the grasses Brizopyrum spicatum, aud Tricus- 

 pis purpurea. 



It would seem that with respect to all the 

 plants we have had under consideration, the 

 presence or vicinity oi salt water is not a neces- 

 sity; but for some the moist sandy soil, and for 

 others, also the modifying influence of large 

 bodies of water, are the conditions suitable for 

 their propagation. 



Probably there are some ten-estrial plants to 

 which salt is an essential element, and which 

 cannot be made to flourish except in the neigh- 

 borhood of that element. Such plants as the 

 Sea Kale (Salsola kali), the Seaside Plantain 

 (Plantago maritima), Marsh Rosemary (Statiee 

 limonium), the Sea-lungwort {Mertcnsia mari- 

 tima), the Samphire (Salicomia), and others 



