Notes on Some Grasses V by Tuguo TATEOKA*

ReceivedDecember 18, 1956

8. Systematic position of the Astrebla The genus Astrebla comprises four species which are endemic in ; A. squarrosa C. E. Hubbard, A. pectinacea F. Muell., A, lappacea Domin and A. elyri noides F. Muell. Bentham (1881), Hackel (1887), F. Ballard (1930) and Gardner (1952) referred this genus to Chlorideae. But Pilger (1954) placed it under Festuceae- together with the genera Triodia, Plectrachne and Notochloa. According to C. E. Hubbard (1928) Astrebla might be most closely allied to Triodia, especially such species as T. lanigera Domin and T. mitchelii Benth. As the species of Astrebla have been hitherto scarcely examined cytologically or anatomically, these views are wholly based on the characteristics of external morphology. Samples of seeds of A. lappacea Domin and A. pectinacea F. Muell. were kindly supplied by Dr. W. Hartley and Dr. N. T. Burbidge. They were grown in our ex- perimental garden. The author's observations of their chromosomes and leaf structure are reported below. Chromosomes'>-In both A. lappacea and A. pectinacea forty small chromosomes are observed in root tip cells (Fig. 1, E • F). Leaf structure-Short club-shaped bicellular hairs and saddle-shaped siliceous cells are found in the upper and lower epidermis of both A. lappacea and A. pecti- nacea (Fig. 1, C • D). In the upper epidermis of both species, long white hairs are visible to the naked eye whose base has a sheath of epidermal cells. Vascular bundles of the two species are surrounded by inner and outer bundle sheaths. The latter is well developed and includes large amounts of chloroplasts. Surrounding the outer sheath, parenchyma cells are distributed radially. Motor cells are well developed. Mechanical cells are found above and below the vascular bundles. (Fig. 1, A • B). As shown above, the leaf structure of the two Astrebla species falls under Chloridoid subtype of Panicoid type according to Prat's (1936) classification. Somatic chromosomes of A. lappacea were formerly examined by Brown (1950), who counted forty chromosomes in accordance with the author's finding. The characteristics of chromosomes and leaf structure of Astrebla species are in good agreement with

* National Institute of Genetics, Mishima, Shizuoka Pref., Japan. 1) Methods for chromosomeobservation-Root tips were fixed by Navashin's solution, dehydrated, and embedded in paraffin. Sections were cut at 15 micra, and stained by Newton's gentian violet method. All the figures were drawn with the aid of an Abbe drawing apparatus. 1,16 植 物 学 雑 誌 第70巻 第826号 昭 和32年4月

Fig. 1. A, B, Transverse leaf sections of Domin x 300. C, Lower epidermis of A. pectinacea F. Muell. x 300. D, Bicellular hairs and siliceous cells x 450. a-b, upper epidermis of A. lappacea. c-d, lower epidermis of the same species. a-f, upper epidermis of A. pectinacea. a, c, e, bicellular hairs. b, d, f, ciliceous cells. E, F, Somatic chromosomes x 2000. E, A. lappacea 7n ; Lf F A _ ha~fiiwrctn 7n = 4a(1 those of many species of Chlorideae : with regard to leaf structure, they show Chlo- ridoid subtype, and in respect to chromosomes they have b=10 and the chromosomes are small. These findings indicate the systematic position of Astrebla in Chlorideae. The relationship between Triodia and was maintained by Burbidge (1953), and de Wet (1956) mentioned the anatomical resemblance of the leaves of two Danthonia species, D. cincta Nees and D. papposa Nees, with those of some Triodia species whose leaf anatomy was examined by Burbidge (1346). In leaf structure and also in basic chromosome number, Astrebla is clearly different from Danthonia. April 1957 $ot. Mag. Tokyo, Vol, 70, No. 826 117

The latter has the basic chromosome number of six and its leaf structure is panicoid or festucoid, but not chloridoid (epidermis-mostly panicoid ; transverse section- mostly festucoid) (de Wet 1954, 1956). While there are various reports on the chromosomes of species which were erroneously included in Triodia, -chromosomes of Triodia sens. str. have not been examined. Further studies on Triodia will demonstrate its systematic position and its relationship to Astrebla.

I wish to express my cordial thanks to Dr. J. Ohwi and Dr. Y. Takenaka who gave me various valuable helps. My thanks are also due to Dr. W. Hartley and Dr. N. T. Burbidge who kindly supplied the seed samples.

Literature cited

1) Baliard, F., Hook. Ic. . Tab. 3142 (1930). 2) Bentham, G., Jour. Linn. Soc. 19: 14 (1881). 3) Burbidge, N. T., Blumea Suppl. 3 : 83 (1946). 4) , Aust. Jour. Bot. 1: 121 (1953). 5) Gardner, C. A., Flora of Western Australia, Vol. 1, Part 1, Gramineae (1952). 6) Hackel, E., Nat. P6. II 2 (1887). 7) Hubbard, C. E., Kew Bull. 28: 257 (1928). 8) Pilger, R., Engl. Bot. Jb. 76: 281 (1954). 9) Prat, H., Ann. Sc. Nat., Bot., lOe serie 18: 165 (1936). 10) de Wet, J. M. J., Amer. Jour. Bot. 41: 204 (1954). 11) -, Ibid. 43: 175 (1956).