PLATE 21.—PLAGIANTHUS CYMOSUS. 
Famity MALVACE/:.] [Genus PLAGIANTHUS, Forst. 
Plagianthus cymosus, 7. Kirk, Students’ Fl. 70; Cheesem. Man. N.Z. Fl. 77. 
This is a very curious and remarkable plant, the life-history of which deserves 
to be worked out with more care than has yet been given to it. It was first collected 
in 1887 by Mr. G. M. Thomson in the vicinity of Dunedin, but I believe that a single 
female was all that was found. Mr. Thomson considered it to be a form of P. betulinus 
and distributed specimens of it under that name. For several years no additional 
locality was discovered, but it was at length gathered by Mr. J. D. Enys in the Upper 
Waimakariri Valley, at an altitude of 2,800 ft.; but, unfortunately, I have no 
information as to the conditions under which it was found. In 1903, or thereabouts, 
Mr. R. H. Matthews collected it near Kaitaia, Mongonu County, at first only 
observing a single male plant, but I understand that several specimens of both sexes 
have since been noted. In 1906 the late Mr. H. J. Matthews and Mr. J. H. Macmahon 
gathered it in the lower part of the Pelorus Valley, Marlborough, where it grows 
in great profusion, intermixed with P. betulinus and P. divaricatus. Lastly, in 1908 
Dr. Cockayne recorded its occurrence on the Port Hills, near Lyttelton. 
P. cymosus can be distinguished from the other species of Plagianthus found 
in New Zealand by the linear-oblong toothed leaves and few-flowered cymes. If 
its characters are carefully compared with those of P. betulinus and P. divaricatus 
it will be recognized that it stands nearly half-way between the two species. The 
suspicion of a hybrid origin at once arises, and it must be confessed that such an 
assumption would go far towards explaining the peculiar rarity of the plant in 
some of its localities. On the other hand, fruiting specimens sent to me by 
Mr. H. J. Matthews from the Pelorus Valley have well-developed and well-ripened 
seeds with a fully developed embryo, and shows no signs of the impaired fertility 
frequently seen in hybrids. 
The late Mr. H. J. Matthews suggested to me that P. cymosus might possibly 
be an arrested juvenile form of P. betulinus. But neither in habit nor foliage does 
it match the common juvenile state of P. betulinus, which has a much more straggling 
mode of growth and broader, shorter leaves. It is much to be desired that 
some botanist residing in a favourable locality would devote a little time and study 
to this puzzling plant. 
Prarr 21. Plagianthus cymosus, drawn from, specimens collected by Mr. H. J. Matthews in the 
lower part of the Pelorus Valley, Marlborough. Fig. 1, part of inflorescence (x 4); 2, flower laid 
open (enlarged) ; 3 and 4, anthers, back and front view (enlarged) ; 5, pistil (enlarged); 6, section 
of same (enlarged) ; 7, fruit (x 4); 8, seed (x4); 9, seed, with testa removed (x5); 10 and 11, 
embryo (enlarged). 
