RypBerGc: SoME GENERIC SEGREGATIONS 277 
11. T. densa (Greene) ; W/. densa Greene, Pittonia, 3: 99. 1896. 
12. T. pumila (Nutt.); J7. pumila Nutt.; Torr. & Gray, FI. N. 
ARS = $3565: 1840. : 
13. T. chrysantha (Engelm.) ; J/. chrysantha Engelm.; Brand. 
Bull. U. S. Geol. Surv. Terr. 2: 237. 1876; MZ. lutea Greene, 
Pittonia, 3:99. 1896. 
14. T. humilis (A. Gray) ; 10 multifforavar. humilis A. Gray, Pl. 
Wright. 1: 74. 1852. 
15. T. multiflora (Nutt.) ; Bartonia multifora Nutt. Jour. Acad, 
Phitacti. £2190. 1847. 
16. T. perennis (Wooton) ; JZ perennis Wooton, Bull. Torrey 
Club, 25: 260. 1808. 
17. T. MULTICAULIS Osterhout, Bull. Torrey Club, 30: 236. 1903. 
AcrouasiA Presl. Rel. Haenk. 2: 39. 1831 
Trachyphytum Nutt. ; Torr. & Gray, Fl. N. Am. 1: 533. 1840. 
This genus was established on a Chilian species, A. dartoni- 
oides Presl, which has fewer ovules (12) and fewer stamens than 
its North American allies, but the structure of the ovary and seeds 
is the same. All the species are annuals and characterized by the 
long cylindric capsules, the filiform placentae and the muricate 
more or less prismatic seeds. Most of the species are small- 
flowered, with linear, lanceolate or ovate-oblong, laciniate, dentate 
or more rarely entire sessile leaves. The following North Ameri- 
can species belong here : 
. A. congesta (Nutt.); 47 congesta Nutt.; Torr. & Gray, FI. 
j Am. 1: 534. 1840; Zrachyphytum congestum Nutt. ; Torr. 
& Gray, |. c. 
2. A. ctenophora; JZ. ctenophora Rydb. Bull. Torrey Club, 28 : 
$3... tool. 
3. A. Tweedyi; I. Tweedyi Rydb. Mem. N. Y. Bot. Gard. 1: 
274; © 2900. 
4. A. albicaulis (Dougl.); J aldicaulis Dougl. ; Hook. Fl. Bor. 
Am. I: 222. 1833; Sartonia albicaulis Hook. 1. c. 
. 5. A. tenerrima ; J/. tenerrima Rydb. Mem. N. Y. Bot. Gard. 
1.2 87. Joe. 
