Bulletin of the Wisconsin Natural History Society Volume 7-9 - Tapa blanda

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1909 Excerpt: ...the oak by their greater shade tolerance. Similar processes may be looked for in the history of the Lake Shore flora. P. The Beach. Dr. Cowles, in his paper on "The Ecological Relations of the Vegetation on the Sand Dunes of Lake Michigan (Botanical Gazette, vol. XXVII, 1899) divides the beach into lower, middle and upper, applying the former name to that portion constantly washed by ordinary summer waves; the middle, to that portion exposed to wave action during storms only; and the upper to that above danger of submersion. This classification is serviceable and based on real distinctions. The lower beach, here as in Chicago, is practically devoid of plant growth. Even the larger boulders of the shingle beaches, where one might expect some lithophilous algae, are usually devoid of such. On the sand beach, however, is found an occasional specimen of Cakilc cdcutula. This most successful of beach plants is enabled to sprout in such places by sending a strong tap root vertically down for more than three inches before it develops any foliage leaves. I have found such seedlings in the cotyledon stage as late as July 20. but whether such venturesome individuals ever reach fructification, I do not know. As a matter of fact, this part of the beach is in some respects less unstable than the higher portion. The sand, being always wet. packs and is not subject to constant shifting, like the drier zone above. (n the pebble beaches. vegetation is entirely absent, not only in the lower, but also the middle zone. The shingle beach, being very narrow, hardly shows zonal differences. But the sandy middle beach is the special abiding place of Cakile. Of course it is very far from covering it,--its plants stand singly, many feet apart; but it is practically the only spe...