326 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 
Heterocentron, while the Heeria of Schlechtendal itself, being a homo- 
hym, must give place to Schizocentron. 
Schizocentron elegans (Schlecht.) Meissn. |. e. 
Heeria elegans Schlecht. Linnvea 18: 452. 1839. 
Rhevia elegans Schlecht. 1. ¢. 
A low creeping vine-like plant forming a dense carpet and rooting at the joints; 
branches terete or nearly so, reddish, somewhat appressed-pubescent; leaves ovate, 
distinctly petioled, obtuse, 5 to 10 mm. long, dark green above, slightly pubescent; 
flowers solitary and terminal on slender peduncles 1.5 to 2 em. long; calyx tube 
about 6 mm. long covered with glandular bristles, the bases (in age) forming 
enlarged closely set tubercles; sepals ovate, 4 mm. long, ciliate; corolla a deep pur- 
ple, 2 to 2.5 em. broad, spreading; 4 anthers sessile, erect, yellowish, 4 reflexed 
and larger, the cells and stalks purplish but the appendage yellowish; ovary crowned 
by a prominent lacerate border. 
Type locality; “pr. Jalapa’”’ & ‘pr. Chiconquiaco.’”’ Only known from the 
region about Jalapa, Mexico. . 
Specimens examined: 
Vera Cruz: in garden at Jalapa, August 13, 1901, J. N. Rose (no. 6081). 
This is a very dainty plant and well worthy of ornamental cultivation. Itis now 
grown in some of the Mexican gardens, but | have no knowledge of its being planted 
elsewhere. I have been told that seed was frequently sent to Germany and possibly 
it has gotten into trade under a different name. Plants are now growing in one of 
the greenhouses of the Department of Agriculture, where it flowered in 1904. 
A SYNOPSIS OF THE SPECIES OF HETEROCENTRON.« 
Out of deference to Professor Cogniaux I have very long delayed restoring the 
Heterocentron of Hooker and Arnott to generic rank, but I have no doubt that if he 
had the material now in the National Herbarium he would not hesitate to make the 
change himself. Into it go all the species of Heeria except H. elegans, all of which 
have heretofore been described under that genus except the new one here proposed. 
I have also restored JT, mexicanum, the type of the genus, which comes from western 
Mexico but which for a long time has been resting under the name of Heeria subtri- 
plinervia, a very different species from eastern Mexico. I. undulatum has also been 
little understood. It seems close to [Z. mevicanum, but Iam inclined to admit the 
species until the types can be more carefully looked into. 
I have not found the characters of the crown used by Triana and Cogniaux to be very 
constant as flowers from the same branch will have the crown setose or naked, The 
following key, while it may require correction and additions, serve to distinguish 
the species in the National Herbarium, 
KEY TO THE SPECIES OF HETEROCENTRON. 
Pedicels glabrous ..........----.--.2222. 2202022 2e-e ee eee eee 1. H. subtriplinervium. 
Pedicels pubescent. 
Calyx tube not glandular. 
Calyx lobes ciliate on the margins ................ ------ 2. HH. macrostachyum. 
Calyx lobes not ciliate on the margins. 
Leaves deep green, narrow (1 to 3.em, broad) ...........------ 3. 1. roseum. 
Leaves pale green, broad (2.5 to 3 em. broad).........----. 4. H. occidentale. 
Calyx tube glandular. 
Calyx lobes ciliate on margin. ............-2-22..2.0222000 . 5. H. undulatum. 
6. H. mexicanum. 
Calyx lobes not ciliate on the margins ..........2..-- eeeeeeeeee 7. H. avxillare. 
@ HETEROCENTRON Hook. & Arn. Bot. Beech. 290. 1840, 
Type species H. mexicanum Hook. & Arn. L. ¢. 
