XOVEMBER 27, 1903.] 



SCIENCE. 



697 



to be done, as my winter's collection of grasses 

 shows, in working out the distribution of 

 genera and species and the relative abundance 

 and economic value of species and individuals. 

 It is almost inevitable that a large number of 

 additional species and some genera will be 

 found, for whole districts of great size and 

 varied climatic and edaphie conditions remain 

 wholly untouched by the botanist. 



A reference to Dr. Stapf's masterly enumer- 

 ation of the Graminea;, in Vol. VII. of the 

 ' Flora Capensis,' shows that there are some 

 130 species of grasses recorded as occurring in 

 the Transvaal. These represent 50 genera, 

 or less than half of the 103 genera recorded 

 for the whole South African flora, which in- 

 cludes the desert region of the Karroo and the 

 subtropical coast region of Natal. Of these 

 50 genera, 44 are represented by species ap- 

 parently indigenous, four — Arundo, Poa, 

 Bromus and Lolium — by species certainly 

 alien, while two, Eleusine and Dactt/loctenium, 

 may perhaps be considered doubtfully in- 

 digenous. 



The limited number of alien species (only 

 about seven) is remarkable as compared with 

 the number found in siich new countries as 

 Cape Colony and California. This is due not 

 only to the isolation of the Transvaal, with 

 no coast-line and separated from the Cape by 

 the Karroo, from the Atlantic coast by the 

 Kalahari, and from the Xatal coast by the 

 Drakensberg, but also perhaps largely to the 

 fact that so little intercourse has been held 

 between its inhabitants and those of adjacent 

 regions. 



Fortunately for the horticulturist, all kinds 

 of alien weeds are at present scarce. 



This state of things can not be expected to 

 last much longer, however, and we shall look 

 for several more alien genera of grasses, with 

 many additional species, to become naturalized 

 within a short period. Judging by analogy, 

 and with the instance of the plateau stock- 

 ranges of the Pacific states of North America 

 fresh in mind, it can scarcely be otherwise. 

 With the introduction of thousands of head 

 of cattle from Cape Colony, Madagascar, 

 Europe and Texas, and of thousands of bags 



of seed-grain from Texas, Argentina, Algeria, 

 Europe and Cape Colony, it would be remark- 

 able if aliens were not largely introduced. 

 Already at least two species of grasses, Poa 

 annua and Sorghum halepense, have become 

 naturalized in the Transvaal, apparently in 

 the short time since the most recent of the 

 material embodied in Dr. Stapf's paper was 

 collected. 



The following species, already established 

 in South Africa, are to be expected as addi- 

 tions to the alien flora of the Transvaal, be- 

 fore very long: Lolium muUiflorum, Hordeum 

 murinum, Bromus viaximus, Bromus com- 

 mutatus, Bromus arvensis, Bromus patulus, 

 Vulpia myuros, Vulpia hromoides, Briza 

 minor, Briza maxima, Dactylis glomerala, 

 Aira caryophyllea, Holcus lanatus, Cynosurus 

 echinatus, Lamarchia aurea, Phalaris minor. 

 Tragus racemosus, Panicum crus-galli, Avetia 

 fatua and Avena sterilis. 



Far more remarkable and interesting than 

 the scarcity of alien grasses is the distribution 

 of the fifty genera among the eighteen tribes 

 of Dr. Stapf's classification. One of the 

 most interesting points is the fact that nine- 

 teen of the genera belong to the two closely 

 related tribes Andropogonea; and Panicese; of 

 the eleven South African genera of Andro- 

 pogoneae and eleven genera of Panicea?, ten 

 and nine respectively are represented by 

 species indigenous to the Transvaal. Of the 

 tribe Chlorideae, nine of the twelve South 

 African genera are represented, while all of 

 the four genera of Eragrostese and the three 

 of Arundinellea; occur. 



On the other hand, we find that the tribe 

 Avenese, with thirteen genera in South Africa, 

 is represented in the Transvaal collections by 

 a single species only. The Hordese with five 

 genera, the Agrosteie with four, the Pha- 

 laridea; and Bambuseae with two, the Pharea; 

 with one, are not represented by a single in- 

 digenous species, while the large tribe 

 Festuceae, with twenty genera (eighteen indi- 

 genous and two alien), has only four native 

 genera and five native species, with two alien 

 genera and two alien species. The Stipese, 

 with three genera, is represented by only one. 



