1958 113

Additional Chromosome Numbers in Transvaal Grasses J. M. J. de Wet Divisionof Botany,Pretoria , SouthAfrica ReceivedJune 15, 1957

The chromosome numbers of South African grasses are studied mainly to get them on record. Some of these data have a direct bearing on the relationships of certain genera . These are discussed in more detail. The genera and species are classified according to Pilger (1954) and Chippendall

(1955).

Material and methods

The material were collected in the veld and identified by Mr . J. A. Anderson. Specimens, together with corresponding root tip slides are filed with the National Herbarium, Pretoria.

Root tips were fixed in Randolph's (1953) fluid , dehydrated and embedded in the usual manner. Sections were cut 14 microns thick and stained in

Stockwell's (1934) solution. Drawings were made with the aid of a camera lucida. The magnification is •~2000 . Anatomical slides were prepared ac cording to Prat (1948).

Results

The species studied are summarized in Table 1. The gramineae is subdivided according to Pilger (1954).

Subfamily Festucoideae: This subfamily includes the tribes classified by

Avdulov (1931) in his series Festuciformes together with some tribes from his miscellaneous series Phragmitiformes.

Festuceae Subtribe Festucinae. Cytologically this tribe is recognized by large chromosomes in multiples of n=7. The genus Festuca as indicated by

Avdulov (1931) is typical in this respect. Moffet and Hurcombe (1949) indicated that Tetrachne is Eragrostoid in respect to leaf anatomy and cytology. This is also true for the genus Fingerhuthia. In these two genera the chromosomes are small and in multiples of n=10.

In respect to leaf anatomical characters the tribe Festuceae is charac terized by the Festucoid type of internal leaf anatomy (Avdulov, 1931, page

33, figure 1). Prat (1936) indicates that typical members of this tribe lack bicellular hairs in their epidermis and the siliceous cells are more or less spherical. In Fingerhuthia, the siliceous cells are saddle-shaped and bicellular

Cytologia 23. 1958 8 Cytologia 23 114 J. M. J. de Wet

Table 1. Chromosome numbers 1958 Additional Chromosome Numbers in Transvaal Grasses 115 hairs are club-shaped (Prat 1936). Moreover , internal leaf anatomy is of the Eragrostoid type. Aveneae sub tribe Aveninae. The genus Agrostis was studied. Large chromosomes in multiples of n=7 were observed. This is in agreement with earlier observations by Avdulov (1931). Arundinelleae. Avdulov (1931) and Prat (1936) demonstrated the Panicoid type of leaf anatomical characters in genera belonging to this tribe. Cytolo gical data exclude it from the Paniciformes. For these reasons it is best classified with Avdulov's (1931) miscellaneous series, the Phragmitiformes. Three genera were studied, Moffet and Hurcombe (1949) demonstrate n=10 in Loudetia. For the same species a somatic chromosome number of 2n-24 was observed in the present investigation. A similar somatic chromosome number was observed in Trichopteryx. The genus Arundinella on the other hand appears to be characterized by n=9. Pappophoreae. The African genera belonging to this tribe were discussed by de Wet and Anderson (1956). A basic chromosome number of n=9 is characteristic for the genera Enneapogon and Schmidtia. Subfamily Eragrostoideae: This subfamily of Pilger (1954) coincides for the greater part with the Chloridoides of Prat (1936). The genera belonging to this subfamily are mostly characterized by small chromosomes in multiples of n=9 or n=10. In the epidermis the siliceous cells are saddle-shaped and the bicellular hairs are club-shaped. The internal leaf anatomy is typical of the Eragrostoid type (Prat 1936, page 220, figure 22). Eragrosteae subtribe Eragrostinae. A number of species belonging to the genus Eragrostis were studied. Most of these were previously investi gated by Moffet and Hurcombe (1949) and Pienaar (1955). Many of the species belonging to this genus are characterized by forms differing in somatic chromosome number. This came about, very likely, through the process of apomixis. Eragrosteae subtribe Sporobolinae. The species studied of the genus Sporobolus are characterized by n=9. One species, S. pyramidalis is of interest. Somatic chromosome numbers of 2n=24 and 30 were reported by Moffet and Hurcombe (1949). For the same species a third chromosome number of 2n=36 was observed. Chlorideae subtribe Euchlorideae. The genus Harpechloa was studied cytologically for the first time. Small chromosomes in multiples of n=10 were observed. Aristideae. The genus Aristida is usually included in the tribe Stipeae of the subfamily Pooideae (Hubbard, 1934). Avdulov (1931) removes the Stipeae from the Pooideae (series Festuciformes) to his miscellaneous series the Phragmitiformes. Pilger (1954) removes Aristida, and justifiably so, from the Stipeae and create a new tribe to include this genus together with Amphipogon and Diplopogon. The latter two genera are unknown cytolo

8* Cytologia 23 116 J. M. J, de Wet gically and anatomically. Aristida appears to occupy an aberrant position in the subfamily Eragrostoideae. Two basic chromosome numbers were

Figs. 1-25. Camera lucida drawings of somatic chromosome numbers in the following grassess. 1, Agrostis barbuligera, 28. 2, A. barbuligera var. longipilosa, 28. 3, A. lach.vantha, 28. 4, Alloteropsis semialata, 18. 5, Andropogon filifolius, 60. 6, Aristida junciformis, 36. 7, Arundinella nepalensis, 54. 8, Brachearia serrata, 18. 9, Digitaria ternata, 30. 10, Eragrostis heteromera, 40. 11, Fingerhuthia africana, 40. 12, F. sesleriaeformia, 20. 13, Festuca costata, 28. 14, Harpechloa falx, 40. 15, Hyparrhenia gazensis, 30. 16, H. rufa, 40. 17, Loudetia simplex, 24. 18, Oplismenus hurtellus, 60. 19, Miscanthidium junceum, 30. 20, Panicum ecklonii, 54. 21, P. natalensis, 18. 22, Setaria sphacelata, 18. 23, Sporobolus fimbriatus var. latifolius, 36. 24, S. pyramidalis, 36. 25, Trichopteryx dregeana, 24.

observed in this genus, n=11 and n=12, by de Wet (1954) and Moffet and Hurcombe (1949). Anatomically this genus is also not typical of the 1958 Additional Chromosome Numbers in Transvaal Grasses 117

Eragrostoideae. Internal leaf anatomy is of the Eragrostoid type. Epidermal traits are variable. For instance, A. ciliata is characterized by the Eragro stoid type of epidermis. Other species, such as A. aequiglumis and A. barbicollis are characterized by the Panicoid type of epidermal traits and species such as A. gracilior and A. obtusa lack bicellular hairs in their epidermis and the siliceous cells are spherical, (Festucoid type). Subfamily Panicoideae: The most homogeneous of Pilger's (1954) subfamilies. Paniceae. A large tribe of which many genera are known cytologically. Eight genera were studied, all of which were known cytologically. Avdulov (1931) reported n=9 in Oplisnienus, the South African species investigated is characterized by n=10. The basic chromosome numbers observed for the remaining genera, Panicum, Brachiaria, Alloteropsis, Digitaria , Paspalum, Setaria, and Cenchrus are in agreement with earlier observations. Subfamily Andropogonoideae: A homogeneous group which is usually included with the Panicoideae (Hubbard 1934) or the series Paniciformes (Avdulov 1931). Andropogoneae subtribe Andropogoninae. All the genea studied were previously known cytologically. The basic chromosome numbers for the genera Bothriochloa (n=10), Hyparrhenia (n=10), Hetcropogon (n=10) and Andropogon (10) have again been encountered. Andropogoneae subtribe Saccharinae. The genus Miscanthidiun with 2n=20 were studied. This somatic chromosome number is in agreement with earlier observations of de Wet and Anderson (1956). Cytologically this genus differs from most other members of the Panicoideae and the Andro pogonoideae in having relatively large chromosomes.

Discussion Cytological and anatomical data suggest that Pilger's (1954) Subfamily Festucoideae includes a heterogeneous group of genera. For these reasons it would be advisable to further subdivide this subfamily. This could be done as suggested by Avdulov (1931) by creating a miscellaneous series, the Phragmitiformes. Pilger (1954) divides the tribes of the Phragmitiformes among five newly created subfamilies with some tribes referred back to the Festucoideae. In such a classification those tribes which are proved to occupy an aberrant position in the Festucoideae could be removed to form a new subfamily. The genus Aristida should be removed from the subfamily Eragrostoideae. Cytological as well as anatomical data points to such a conclusion. For the same reasons Aristida is also excluded from the Festucoideae. The position of this genus in grass phylogeny is difficult to ascertain. 118 J. M. J. de Wet Cytologia23

Summary

The chromosome numbers were counted in 47 species and varieties belong ing to 25 genera oft he family Gramineae. Four genera, Arundinella (n=9), Fingerhuthia (n=10), Harpechloa (n=10) and Trichopteryx (n=12) were previously unknown cytologically. Eighteen species and varieties belonging to various genera were studied cytologically for the first time. In addition eight species and varieties studied are characterized by chromosome numbers differing from earlier reports. Cytological and anatomical data suggest that Fingerhuthia occupies an aberrant position in the tribe Festuceae and should be removed from the subfamily Festucoideae. It was indicated that this subfamily is far from homogeneous. The genus Aristida differs from other members included in the subfamily Eragrostoideae in cytology and leaf anatomy.

Literature cited Avdulov,N. P. 1931. Karyo-systematischeUntersuchungen der Familie Gramineen. Bull. Appl. Bot. Pi. Breed. Suppl. 44: 1-428. Burton, G. W. 1940. A cytologicalstudy of some species in the genus Paspalum. Jour. Agric. Res. 60: 193-198. Chippendall,L. K. A. 1955. The classificationof grasses. Grassesand pastures of South Africa: 1-527. de Wet, J. M. J. 1954. Chromosomenumbers of a few SouthAfrican grasses. Cytologia19: 97-103.- and Anderson,L. J. 1956. Chromosomenumbers in Transvaal grasses. Cytologia21: 1-10. Hubbard,C. E. 1934.Gramineae J. Hutchinson: The families of floweringplants 2: 199 -299. Kupkro, S. 1953. Karyologicalstudies and chromosomenumbers in Hyparrhenia aucta and H. hirta. Jour. S. Afr. Bot.: 31-58. Moffet,A. A. and Hurcombe,R. 1949. Chromosomenumbers of South African grasses. Heredity 3: 369-374. Nielson, E. L. 1939. Grass studies III. Additional somatic chromosomecomplements, Amer. Jour. Bot. 26: 366-372. Pienaar, R. de V. 1955. The chromosomenumbers of some indiginousSouth African and introducedGraminea. Grassesand pastures of South Africa: 551-570. Pilger, R. 1954. Das System der Gramineae. Bot. Jahrb. 76: 281-384. Prat, H. 1936. La systematiquedes Graminees. Ann, Sci. Nat. Bot. 10: 165-258.- 1948. General features of the epidermisin tea mays. Ann. MissouriBot. Gard. 35: 341-351. Randolph,L. F. 1935. A new fixing fluid and a revised schedulefor the paraffinmethod in plant cytology. Stain Techn. 10: 95-96. Stockwell,P. 1934. A stain for difficultplant material. Science80: 121-122.