188 Transactions. 



Art. XVIII. — On Danthonia nuda Hook. f. and Triodia Thomsoni 



(Buchanan) Petrie, comb. nov. 



By D. Petrie, M.A., Ph.D. 



[Read before the Auckland Institute, 28th November, 1911.] 



Lx my herbarium there is a good specimen of Danthonia nuda Hook, f., 

 collected at a high elevation on the Ruahine Range, Hawke's Bay. 

 There can be little doubt that this plant is a true Danthonia, though it 

 makes some approach to the genus Triodia. Sir J. D. Hooker's descrip- 

 tion of it is brief, and wanting in some important details. The culms are 

 very slender, leafy, and but little longer than the leaves. The sheath of 

 the" topmost cauline leaf is three or four times as long as the blade, which 

 reaches to the base of the panicle. The flowering-glumes show considerable 

 variation in the hairy covering, which is more ample than one would 

 suppose from Hooker's description. Besides the one or two small tufts 

 of hairs on the sides of these glumes, there is usually a scanty band 

 of sparse hairs across the back just above the middle, and often also 

 a few straggling hairs lower down but above the basal tuft. The awn, 

 which is quite straight, is one-third as long as the glume. The florets in 

 each spikelet are more commonly 2 than 3. 



I have a few indifferent pieces of what is most likely this species from 

 the Tararua Range, collected by that excellent observer Mr. B. C. Aston. 

 Unfortunately, they are all past flower. 



Danthonia nuda has long been confounded, and by myself in the first 

 instance, with a somewhat similar grass, the Danthonia Thomsoni of 

 Buchanan. The latter was discovered by me at Mount St. Bathan's, 

 Central Otago. As it has a wide distribution in districts explored by 

 Hector and Buchanan, and also by Von Haast. it is singular that it was not 

 found before. It may have spread and increased since*these early explora- 

 tions were made, but I consider it much more likely that it was merely 

 overlooked or mistaken for some other species that was collected then. 

 At present it has a wide distribution in the upland districts of South 

 Canterbury, Otago, and Southland. It is fully and accurately described 

 in Mr. Cheeseman's Manual under the name Danthonia nuda Hook. f.. 

 though he notes that his plant may not be the same as Hooker's. 

 The grass is not, however, a Danthonia., but a characteristic species of 

 Triodia, to which I now give the name Triodia Thomsoni. It was 

 originally named in compliment to Mr. G. M. Thomson, and I am 

 special lv pleased to be able to associate permanently with it the name 

 of this old and valued friend. As a pasture-grass Triodia Thomsoni 

 possesses a high value. It has a fair amount of foliage, is deeply 

 rooted so as to withstand drought and exposure to drying winds, and 

 is palatable and highly nutritious. It forms one of the most common 

 and useful of the bottom grasses of the tussock-steppe in all the 

 upland districts through which it ranges, and is much eaten by sheep. 

 It is well worth artificial cultivation, and promises to help in reclaiming 

 the now desert and semi-desert lands from which the native pasture 

 has disappeared through long-continued overstocking. 



Triodia Thomsoni differs from Danthonia nuda in the narrow panicle 

 with erect branches, the longer less-leafy culms that greatly exceed the 

 leaves, the longer narrower more numerous spikelets that usually contain 

 5-7 nearlv glabrous florets, and the much shorter less rigid awns. 



