I N systematic works dealing with Gentianeae, Bartonia and Obolaria are invariably placed side by side on account of the following characters: ' Lobes of the corolla imbricated in the bud, i. e. two exterior and two interior; no appendages ; ovules and extremely numerous, minute, dosecoated seeds covering the whole parietes of the ovary and capsule ; stamens inserted in or little below the sinuses of the corolla; anthers ovatesagittate ; 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 s. Characteristic of the latter is the colour of the anthers, being sometimes purplish or dark maroon, besides the calyx being
