164 Rhodovs Gs 
the presence of broad white appendages, often tinged with pink, on 
the involucral glands. E. Zpecacuanhae has often been described as 
having exappendiculate glands, but Norton! has pointed out that a 
narrow green appendage 
is always present. Partly 
on this ground he excluded 
the species from the sub- 
genus Tithymalus. Dr. 
Small? transferred it to 
Tithymalopsis, and the 
discovery of E. arundelana 
Fig. 1. Euphorbia arundelana. Expanded invol- : dit : 
ucre showing broad appendages. (X 5) shows that its affinity 1s 
really with the members 
of this group. In £F. Ipecacuanhae the appendage is so inconspicuous 
as to be easily overlooked, in E. arundelana, on the other hand, it is 
quite as conspicuous as in the familiar E. corollata. (Compare the 
text figures.) The range of variation seems to be as great in E. 
arundelana as in E. Ipecacuanhae, but the 
two series of forms present the follow- 
ing contrasting characters. 1) Some 
forms of E. arundelana (not all) are pu- 
bescent. In Anne Arundel County there 
seem to be no pubescent forms of F. 
Ipecacuanhae, nor are there any pubes- Fig. 2. Euphorbia Ipeca- 
cent specimens of it in the National  Cusmhae. Expanded involucro 
Herbarium. The presence of pubes- dages. (x 5) 
cence is therefore diagnostic; its ab- 
sence is not. 2) In the forms of E. arundelana the stems are prevail- 
ingly of strict, upright habit, whereas those of E. Ipecacuanhae tend 
to be spreading or decumbent. In other characters the two species 
are strikingly alike. It is especially noteworthy that the finger-thick, 
deep, vertical roots are indistinguishable. 
Euphorbia arundelana sp. nov. Herba perennis habitu Euphor- 
biae Ipecacuanhae simillima. Radix perpendicularis longissima 
crassitudine circa 1 cm., caulibus subterraneis multiramibus plus 
minusve tortuosis coronata. Caules plures floriferi annui, altissimi 
1 J. B. S. Norton, Report Mo. Bot. Gard. XI (1900), p. 86. 
? J. K. Small, Flora Southeastern U. S., p. 1334. 
