Bartonia, Muehl. An Anatomical Study. 
BY 
THEODORE HOLM. 
With Plates XXXIII and XXXIV. 
I N systematic works dealing with Gentianeae, Bartonia and Obolaria are 
invariably placed side by side on account of the following characters : 
c Lobes of the corolla imbricated in the bud, i. e. two exterior and two 
interior ; no appendages ; ovules and extremely numerous, minute, close- 
coated seeds covering the whole parietes of the ovary and capsule ; stamens 
inserted in or little below the sinuses of the corolla ; anthers ovate- 
sagittate ; foliage hardly any or discoloured ’ (Gray : Synoptical Flora of 
North America). Or ‘corolla efoveolata, lobis imbricatis’ (Bentham et 
Hooker). A like characterization is offered by Gilg (Natiirl. Pflanzenfam. 
iv, 2 ), but with the additional remark : ‘ Schwachgriine Halbsaprophyten.’ 
By Bentham, Hooker, and Baillon these genera are placed among the 
Swertieae, by Gilg among the Erythraeinae. 
In regard to Obolaria the writer has, some years ago, described some of 
the most salient points in its external and internal structure 1 , and we 
have shown that the corolla does possess nectaries in the shape of small, 
fringed scales, besides that the plant contains chlorophyll in abundance, 
and that the corallioid roots represent mycorhizae. In habitus the 
genus differs very much from Bartonia ; it is a rather robust plant in 
proportion to its size, and the fleshy leaves are very conspicuous. In 
Bartonia , on the other hand, we meet with plants of exceedingly slender 
habit, threadlike stems and minute, subulate leaves. Common to both is 
the presence of chlorophyll and corallioid mycorhizae. 
When Gray (1. c.) described Bartonia only two species were known : 
B. verna , Muehl. and B. tenella , Muehl., the latter with a variety Moseri. 
Since then two more species have been established, viz. B. lanceolata , Small 2 , 
and B. iodandra , Robins 3 . Characteristic of the latter is the colour of the 
anthers, being sometimes purplish or dark maroon, besides the calyx being 
1 Annals of Botany, vol. xi, no. xliii, September, 1897, p. 369. 
2 Flora of the South-eastern United States, 1903, p. 932. 
3 Botan. Gazette, 1898, p. 47, and Rhodora, vol. ii, p. 56. 
[Annals of Botany, Vol. XX. No. LXXX. October, 1906.] 
