OCCURRENCE OF CAREX HELVOLA IN BRITAIN. 461 
being laxer and having the appearance of being punctulate. 
Hitherto I have been unable to find mature fruit of C. helvola, 
either in the many specimens which I have examined from 
Norway or from Ben Lawers, but even in young C. canescens 
from Berkshire the ribs on the perigynium can be observed. 
The perigynia are also somewhat shorter than in C. canescens, 
and are more oblong in shape than the perigynia of a closely 
allied plant issued in the “Herbarium Normale” of Schultz 
and Dörfler (n. 3289) and named Carex Zahnii |C. approzi- 
mata x Persoonii], Kneucker in * Deutsche Botan. Monatsschrif t, 
lx. (1891) p. 60, which has been found on the ascent of the 
Grimsel growing with both its assumed parents. In this plant 
the perigynia are abruptly narrowed at both the base and the 
apex so as to give it a skate-like appearance, and there is 
more brownish coloration than in cur C. helvola. In external 
appearance C. Zahnii bears a closer resemblance to our C. helvola 
than that plant does to the Scandinavian C. helvola collected 
by G. Blytt in Landers; indeed from outward appearance 
C. Zahnii could scarcely be distinguished from our C. helvola, 
but the shape of the sterile fruit differs as I have said considerably. 
I do not lay great stress upon the shape of immature and sterile 
perigynia. 
Another plant which bears a close superficial resemblance 
to our C. helvola is C. pseudohelvola (C. canescens x norvegica), 
Kihim. in Herb. Mus. Fenn. ed. ii. p. 125-6, issued iu the 
same “ Herbarium Normale” (n. 3095) and coming from arctic 
Norway ; but in this plant the perigynia are distinctly ribbed, 
the spikes more compact, and the spikelets arranged in the 
manner characteristic of the Cyperaceæ, while in our plant they 
have a spuriously distichous arrangement, the spike having a 
flattened appearance. , 
The question may be asked, Is C. helvola a good species P , 
Against this supposition may be urged the uniform sterility, 
seeing, as I have said, that in the many Scandinavian and Scottish 
specimens which I have examined l have not been able to find 
à mature fruit. Is it then a hybrid or a sterile form? Ifa 
hybrid, I should have no difficulty in suggesting C. canescens 
a one of the parents, but should have great hesitation in 
naming the other. Dr. Christ has replied to my query: 
“Jai toujours pensé que le C. helvola de Blytt est une de ces 
espèces qui doivent leur origine à deux plantes, et ces plantes 
