——e 
BOX-ELDERS, REAL AND SO-CALLED 133 
in the U. S. National Herbarium, and, I think, can hardly be 
considered as even nearly related to Lindheimer’s plant. Recog- 
nizing this Pax later segregated these first mentioned plants under 
the name Acer Negundo var latifolium Pax, 1889, |.c.,and transferred 
Lindheimer’s plant as a variety of Acer californicum, as 
Acer californicum var texanum Pax, 1889. ‘The plant is really 
more closely related to the Californian tree than to the eastern 
tree of the Atlantic States and mostly east of the Alleghany 
Mountains. Even Lindheimer’s type appears, however, hardly 
to deserve specific rank, and is in fact only a less densely pubescent 
Rulac californicum. It seems that when the Rocky Mountain 
plant began to become numerous in herbaria, this really unnamed 
and totally different species from any of the forgoing in some 
manner became confused with the Texan form or variety, and 
received the name Ru/ac texana.* Dr. Britton recognizing its differ- 
ence and the confusion named it Acer interior, as | have already 
noted. In 1902 Paxj still recognized the varieties mentioned and 
in the same sense as last emended in 1889, but specimens of 
Britton’s plant as well as Nuttall’s are scattered throughout the 
numerous subvarieties and forms, of his monograph. Wesmael§ like 
Pax had published many varieties and subspecies. Considering 
the great variability of the form of foliage of the plants, one not 
knowing that a single tree may have several kinds, shapes, not 
only at various ages, but at one and the same time, would readily 
be led to multiply, as has- actually been done, the varieties and 
subspecies until we have a perfect maze of names. It is hardiy 
safe to multiply such without an ecological study of the whole 
plants in their native haunts. I have found several of these so- 
called varieties on the same individual plant! Our midland Box- 
elder, the one Nuttall first described, has been found to have the 
terminal leaflet broader than long on seedlings and two year old 
plants early in the season, whereas, the later leaves are the same 
as on the larger trees. I think I can be sure of this as I have 
examined the antecedants of the plants in question in our locality. 
I have also found that one of the principal characters on which 
Dr. Britton’s Acer interior is based, 2. e., attenuation of the base of 
the fruit, varies at least in those plants of the species growing in 
* See Small, J. K. Flora of the S. E. United States, 1903. 
+ Pax, in Engler & Prantl’s Pflanzenreich. 1902. 
t Wesmael, A. Bull. Soc. Roy. Bot. Belg. 1890, XXIX. pp. 42, 43. 
