183 
rocks. Z. Greenmanii occurs on volcanic ground, Sierra de Ajusco, 
8500 feet altitude; 7: xapiforme in the Pedrigal at Thapam, 7300 
feet altitude. Both of these plants are succulent, consolidated and 
well adapted to stand the long periods of draught which are the 
rule in these volcanic regions. The roots penetrate into the vol- 
canic pockets, where they find enough of soil for their needs. 
The leaves of both are terete, clustered at the base and surround a 
much abbreviated flower-stalk. It is interesting to note, that two 
other species of the genus, namely 7: confertiflorum,* and 7. 
humile,+ are found in the Pinos Altos mountains, New Mexico. 
Another species, Zalinum spinescens, is also adapted to dry situa- 
tions, as shown by its dwarf habit and terete leaves. It was 
discovered by T. S. Brandegee on bare hills east of Ellensburgh, 
Washington. 
Before describing the particular structure of 7alinum tereti- 
folium, as determined by microscopic examination, it is expedient 
to describe the two species, one new, found by me this summer 
while botanizing with the veteran collector and botanist, Mr. 
C. G. Pringle. 
I. TALINUM NAPIFORME DC. 
Roots perennial, somewhat tuberous, I-2 in. long, % in. broad, 
swollen with rounded button-like knobs and covered with corky 
scales of a dark brown color and bronze-like lustre ; scales protec- 
tive, root fibres long and rooting in the crevices of the rocks; 
acaulescent; leaves terete, smooth, waxy-green, flattened at base, 
rounded acute, 1-244 in. long, clustered at top of root; scape 3-8 
in. tall, cymosely many-flowered ; bractlets small, sessile, acute ; 
flowers small, ¥%. in. across; sepals 2;+ petals 5,§ white veined 
with purple; stamens 5 ; ovary short, rounded ; style short ; stigma 
capitate, hispid; fruit small, 1 in, long, 3-cornered, sutural dehis- 
cence; seeds small, black, spirally grooved. (Plate 299, fig. 3.) 
Valley of Mexico, Tlalpam, Pedregal, growing on volcanic 
rocks. Resembling 7. confertiforum of E.L.Greene. Distributed 
in Pringle’s Plantae Mexicanae as no. 6487. 
2. TALINUM GREENMANII 0. Sp. : 
Tap-root spindle-shaped, forked or straight, 2 in. long ; acaules- 
* E. L. Greene, Bull. Torr. Club, 8: 121. 
+ E. L. Greene, Bot. Gaz. 6: 183. 
$ Called bracts by Warming, 
§ Called perianth by Warming. 
