48 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 



Panicastrella Americana, major, annua, spica laxa, purpurascente. Micheli, 

 Nova PI. Gen. 36. pi. 81. 1729. The phrase names of Sloane and of Plukenet 

 given above as pertaining to C. echinatus are cited, but Sloane's phrase is 

 changed by omitting " vel alba." The figure is a crude illustration of a 

 Cenchrus bur. Micheli does not indicate which of his two species it is meant 

 to show. 



Panicastrella Americana, minor, annua, spica angustiori, densa, albicante. 

 Micheli, op. cit. 37. " Gramen echinatum, maximum, spica alba. Sloan." is 

 cited. Sloane's name, " spica rubra vel alba," applies to C. echinatus. 



Linnaeus first describes the genus Cenchrus in the second edition 

 of the Genera Plantarum, 1 placing it in his class " Polygamia 

 monoecia," between Aegilops and Valantia (a genus of the 

 Rubiaceae). The description is as follows: 



" CENCHRUS*. Panicastrella Mich. 31. 

 Cae. Involucra plura, laciniata, echinata, in capitulum congesta : singulis 



sessilibus tres calyces includentibus. 



Perianthium Gluma bivalvis, lanceolata, concava, acuminata, biflora, corolla 



brevior. 

 Cor. altera mascula, altera hermaphrodita. 



Propria singula bivalvis : valvulis lanceolatis, acuminatis, eoncavis. muticis : 



interiore minore. 

 Stam. singulis Filammta tria, capillaria, longitudine corollula > , Antherw 



sagittate. 

 Pist. Hermaphroditis Germen subrotundum. Stylus filiformis, longitudine 



staminum. Stigmata duo, oblonga, pilosa, patentia. 

 Per. nullum. 

 Sem. subrotundum. 



This description is copied exactly in the second, third, fourth, and 

 fifth editions. In the Species Plantarum, 2 from which under botani- 

 cal codes the name dates, Linnaeus includes five species : 1. G. racemo- 

 sus (Nazia racemosa Kuntze), 2. C. capitatus (Echinaria capitata 

 Desf.), 3. G. echinatus, 4. C. tribuloides, 5. G. frutescens. The generic 

 description given above applies only to G. echinatus and G. tribu- 

 loides. In the first two species there is nothing that could be called 

 an involucre including the flowers, the spines being borne on the 

 glumes in the first and being the lobes of the lemmas in the second. 

 The two florets described, one masculine, the other hermaphrodite, 

 are found only in the third and fourth species. From the description 

 it is evident that Linnaeus had dissected a bur of some species of 

 Cenchrus, and the three " calyces " noted point to C. echinatus as the 

 species he had, since in C. tribuloides there are rarely more than two 

 spikelets. The fifth species, G. frutescens is not identifiable. The 

 description is as follows : 



" CENCHRUS capitulis lateralibus sessilibus. foliis mucronatis, caule 

 fruticoso. 

 " Arundo graminea aculeata. Alp. exot. 105. t. 104. 



1 493. 1742. 2 1049. 1753. 



