136 



BOTANICAL GAZETTE 



[febeuary 



type of T. intermedia Nash (Nash 2426) was found to contain these cleis- 

 togenes, and judging by the swollen sheaths they were abundant. This is 



true also of specimens of the same species from Cape Florida {Chase ^9 $9)- 

 Of r. purpurea (Walt.) Chapm., practically all the late collections contained 



these spikelets. Hence this habit 

 of producing two forms of cleisto- 

 gene belongs to the entire genus. 

 Unlike the dichotomous species of 

 Panicum, in which only the cleisto- 

 genes perfect their grains, the 

 terminal spikelets are fruitful in 

 Triplasis as well as the two forms of 

 cleistogene. The presence of these 

 cleistogenes at the nodes explains 

 the habit, common to the three 

 species, of disjointing at the lower 

 nodes when dry. 



Another interesting point in the 

 habit of cleistogamous grasses de- 

 veloped in the field-work of last 

 October. Amphicarpon amphi- 

 carpon (Pursh) Nash w^as found 

 with perfectly developed grains in 

 the aerial spikelets. These speci- 

 mens were collected in the border 

 of a cypress swamp between Wil- 

 mington and the eastern coast of 

 North Carolina (Chase 4597). After 

 noting these fruitful spikelets, practically all the plants in the small colony 

 were examined. Derhans a finnHrpH anri oK/^ti* f;f+««^ ,,-0^0 fi^nnrl wJth 



Fig. X. Base of intemode showing pro- 

 phyllum inclosing cleistogamous spikelet. 

 X4* — Fig. 2. Cleistogamous spikelet. 

 XS. — Fig. 3. Grain from same. X8. — 

 Fig. 4. Spikelet from terminal panicle. 

 X8. — Fig. 5. Grain from same. X&. — 



B<:^ SDikelet'; draxorr frnm t>toe^rv^^ ^1^«*- 



fruiting aerial 



spikelets also, 

 sterile. 



spiiielets. Most of these possessed developed subterranean 

 The aerial spikelets have heretofore been supposed to be 



The earlier antlinrc — Pt^t?ctx tT-V,rt 



earlier authors — Pursh, who first described the species 

 under Milium, Kunxh, and Bentham—c ailed them staminate and the 

 subterranean spikelets pistillate. It is doubtless very seldom that these 

 aerial spikelets develop tiieir grains. Herbarium material was examined 

 tod a single specimen of .4. amphicarpon from Delaware {Commons 18 of 

 1895) was found with fertile aerial spikelets. No such spikelets were 

 found in .4. fioridamm Chapm.— Agnes Chase, U. S. Department 0} 

 Agfictdture, Washington, D, C. 



