28 .■..-.;; . v • Rhodora , •■ •■ [February 



As for tlie age of those coastal plain species, some of them seem to 

 be a little older than I formerly supjiosed. DuHchium has recently 

 been reported in a fossil state from interglacial deposits in Denmark/ 

 and in Dr. Knowlton's catalogue of Cretaceous and Tertiary ])lants 

 of North America (Bull. 152, U. S. Geol. Surv., 189S) Chanmecyparis, 

 Brasenia, Drosera rotundifolia and several existing species of Pota- 

 mogeton are reported from Pleistocene deposits in Canachi or New 

 Jersey, and Celthra alnifolla and Leucothoe racemom from ^Miocene 

 in New Jersey. Hut on account of the fragmentary nature of the fos- 

 sil material it is perhaps not safe to claim absolute sp<"cific identity 

 with living plants. Dr. Ilollick, who rejxM-ted the two last-nameil 

 species, now admits that their specific relationshijis are verv doubtful. 

 It is altogether likely however that some of the species mentioned in 

 my former list are of more recent origin than others, and it may some 

 time be possible to classify them according to age with some certainty. 



The glacial-coastal jjlants would seem t« be as a rule somewhat rare 

 in the northern states, judging from the numerous lists of rare plants 

 or additions to local floras which have ai)])eared in Hhoiwha since its 

 inception, several of which consist largely of just such species.^ 



The following species and genera might be added to the list of those 

 confined to the glaciated region and coastal jjlain, or nearly so. 



Zizania nqmifica !>. West to Manitoba, south to Florida, AVest Ten- 

 nessee and Texas. Also in Asia (if it is all the same species). In the 

 Atlantic coastal plain states this seems to be chiefly confined to brack- 

 ish marshes, while in the glaciated region it is said to grow in lakes. 

 There are some slight differences between the northern and coastal 

 plants, which may indicate an incipient differentiation into two species.^ 



Hemicarpha mieranfha (Vahl) Britton. West to Michigan and 

 Nebraska, south to Florida, Illinois, Missouri and Mexico. (Not 

 known in Georgia.) Also reported from the West Indies and South 

 America, but theri> may jiossibly be more than one species involved. 



Carex bullata Schk. West to Lycoming County, Pennsvlvania 



'See Hartz, EiiKler Bot.Jahrl). 36: 78-81. /. 1-4. Feb, 28, 1905, Berrv Bot Gaz 

 39: 232. March, 1905. ; 



■' For example the [japers by Mr. Harder in June, ISOO, Mr. Knowlton in June and Octo- 

 ber. 1900, Dr. Haberer in May and June. 1905, and Dr. Lewis in October, 1905- and my 

 own in 1899 and 1900. 



■■'See Brown & Scofield, Bull. 50, Bureau Plant Industry U. S. Dept. Agr 1903- Sco- 

 field. Bull. 72 pt. 2. 1905. 



