44 2 Holm. — Bartonia , Muehl. An Anatomical Study. 
turbinate below. The former, B. lanceolata , is characterized by possessing 
lanceolate corolla-lobes, which are entire, acute or acuminate, in contrast to 
B. tenella in which the corolla-lobes are oblong and erose ; but the differ- 
ences in the structure of the stigma are not mentioned. In regard to the 
geographical distribution of these species, B. verna occurs in the southern 
States from S. Virginia to Florida and Louisiana ; B. tenella and B. lanceolata 
are widely dispersed in the Atlantic States from Connecticut to Florida, 
west to Wisconsin and Arkansas ; while B. iodandra is a more northern 
plant, having been found only in Newfoundland, Nova Scotia, and Massa- 
chusetts. In the District of Columbia and Maryland B. lanceolata is the 
only species that has been observed by the writer. It would thus appear 
as if B. verna and B. iodandra occupy a more distinct geographical area 
than the others, even if these have not, so far, been found directly associ- 
ated with each other. 
In regard to the specific merits of these four plants, B. verna is perhaps 
the most constant and the most readily distinguished. Besides being 
vernal (the three others are autumnal), the pure white corolla and the com- 
pressed ovary make it very distinct. The lobes of the corolla are spreading 
(Plate XXXIII, Fig. i), one-nerved, obtuse and very minutely erose (Fig. 2) ; 
the stigmatic surface (Fig. 4) of the ovary is long and very prominent. 
In B. lanceolata the corolla-lobes are erect (Fig. 9), lanceolate, more 
or less involute along the margins, and three-nerved (Fig. 7), besides 
that the colour is yellowish to white ; the ovary of this species (Fig. 10) 
is quadrangular in cross-action, and the stigmatic surface very small, not 
extending beyond the corolla (Fig. 9). In B. tenella , on the other hand, 
the lobes of the corolla (Fig. 18) are oblong, obtuse, erose and three-nerved, 
and the colour is frequently more or less purplish ; the stigmatic surface 
(Fig. 19) is very conspicuous and raised above the corolla (Fig. 17). 
Intermediate between B. lanceolata and B. tenella is the little-known 
B. iodandra , in which the flesh-coloured corolla-lobes are broadly oblong 
and obtuse, while the stigmatic surface is small and does not reach beyond 
the corolla. The flowers are usually somewhat larger than those of 
B. tenella , and the calyx is, as already stated, turbinate below. It may be 
that B. iodandra represents a mere geographical form of B. tenella. 
The inflorescence is a cyme in all the species, but often somewhat 
irregular on account of the leaves being, sometimes, not exactly opposite, 
and this is especially the case with B. iodandra , besides in weak, few- 
flowered specimens of B. lanceolata (Fig. 5). Small, one-flowered specimens 
of B. verna are common, while the largest number of flowers observed in 
this species is nine ; but three-flowered individuals appear to be the most 
frequent. In B. tenella and B. lanceolata (Fig. 6) the inflorescence is often 
ample and rich-flowered. 
Characteristic of these species are the minute, appressed leaves, normally 
