82 Rhodora [May 
nerve, continuous with stipe and style, gives off parallel transverse 
nerves which anastomose at the edge of the body, forming a “ circum- 
vallation.” In variety cryptoneura (so named because the fruit does 
not show the transverse body nerves and their anastomoses at the 
inner edge of the wing) the stipe of an unskeletonized samara shows 
but one nerve, notwithstanding the fact that the two lateral nerves 
are as well developed as in P. mollis, and can be exhibited by removing 
the overlying tissues. Since in these two plants the presence or ab- 
sence of “circumvallation” depends upon the varying thickness of 
the loosely cellular tissue under the epidermis, Į have not regarded it 
as of more than varietal worth. 
Ptelea mollis var. cryptoneura var.nov. Frutex humilis patens, 
ramulis atro-purpureis, vetustioribus glabris, junioribus puberulis. 
Folia matura coriacea crenata, supra pallido-viridia sparsim crispo- 
pubescentia, subtus albicantia perdense pubescentia; foliolis ovatis 
apice acutiusculis, obtusis vel rotundatis, lateralibus basi abrupte an- 
gustatis; terminali lateralibus dimidio longiore, basi sensim angustato. 
Samarae 1.7-2.2 cm. longae, ovatae, vel fere orbiculares, apice emar- 
ginatae; centro nervos transversos et eorum confluentes ad alae 
insertionem solum obscurius exhibente, dense fusco-punctato; ala 
pallido-straminea sparsim punctata.— Bartlett 951, 1 Sept., 1907, 
and 1748, 10 Aug., 1909, sand-hills and pine barrens near Thomson, 
McDuffie Co., Georgia. This variety differs from the specimens of 
Ptelea mollis distributed by the Biltmore Herbarium in the following 
minor points besides those already enumerated:— the leaflets are 
not abruptly acute at the apex; the body of the samara is more densely 
punctate; the samara is more nearly orbicular; the twigs are not 
glabrate until their second season. 
Bureau or PraNT Industry, Washington, D. C. 
REPORTS ON THE FLORA OF THE BOSTON 
DISTRICT,— X. 
In the genus Scirpus there are seven species or varieties which have 
been reported from only a single place, while numerous others have 
only a few known stations. Three or four of these are recent segre- 
gates, which have not been collected much since their characteristics 
