62 B Canadian Arctic Expedition, 1913-18 



caudex; leaves silvery-canescent with firm very close-pressed pubescence; 

 radical twice ternately or quinately divided or parted into oblong-linear 

 or narrower lobes (of only 2 or 3 lines in length); cauline sparse, mostly trifld; 

 heads comparatively small (2 lines high), several or rather numerous in a strict 

 and simple racemiform inflorescence, fuscous; corolla pilose or sometimes 

 glaborus. — A. arctica and A. caespitosa, Bess in Hook. Fl. I, 323, 324. Arctic 

 coast to Bear Lake." 



A. comata Rydb. 



In specimens from "Sandspit at Martin point," the numerous, dense 

 rosettes of leaves are developed at the apex of short, very much branched, sub- 

 terranean stems with an abundance of thin, profusely branched secondary 

 roots. In specimens from "Gravel-tundra at Collinson point" there are long, 

 subterranean stolons, quite thick, but with onlya few roots, which are quite 

 slender; in such specimens the cushion-structure is less pronounced. 



Petasites frigida (L.) Fr. 



This is one of the species which by several authors have been referred to 

 Nardo&mia Cass, on account of the corollas of the pistillate flowers being ligulate. 

 By Reichenbach Nardosmia has been reduced to a mere section of Petasites, 

 and so it is accepted also by Bentham and Hooker. Among the species of the 

 section Nardosmia, N. glacialis Ledeb. and N. Gmelini DC. have the basal 

 leaves developed almost contemporarily with the flowers, while in the other 

 species as well as in Petasites s.s. the inflorescence appears earlier than the 

 leaves. 



From a morphological viewpoint the genus Petasites offers several points of 

 interest, for instance with regard to the structure of the rhizome; in this respect 

 several species have been discussed by Hjalmar Nilsson,' viz. : P. alba (L.) Gaertn., 

 P. spuria (Retz.) Reich,, and P. officinalis Moench. 



In these the rhizomes bear series of membranaceous, sheathing leaves, 

 destitute of blades, and some with blades and long petioles. In P. frigida the 

 following structures have been observed. In a fruiting specimen from Herschel 

 island, collected in August, the horizontally creeping rhizome bears a tall (22 

 cm.) flower-bearing stem, and at the base of this the rhizome continues as a 

 horizontally creeping stolon, consisting of six internodes. The first three leaves 

 are scale-like, but after these follow two long-petioled, green leaves, situated 

 very close together, while the leaves of the apical portion of the rhizome are merely 

 scale-like. A fragment of a stolon from the same locality (Fig. S : 2) illustrates 

 this structiu-e. In another specimen (Fig. 1) from the south coast of Coronation 

 gulf, collected in July, the rhizome bears a tall, flower-bearing stem at the base 

 of which two young, green leaves are situated. The apical portion of the rhizome 

 bears four scale-like leaves, of which the foremost partly surrounds two, very 

 young, green leaves. In other words, the rhizome is undoubtedly a monopodium 

 with the flower-bearing stem axillary, as shown in figure 1. Moreover, it would 

 appear as if the green leaves (Fig. 2) represent a very short vegetative branch, 

 developed in the axil of a scale-like leaf. Concerning the root-system, secondary, 

 long and slender roots proceed from the internodes; they are especially abundant 

 close to the floral shoot. 



The fact that P- frigida very seldom develops flowers in the arctic region, 

 and that it must depend, to a very considerable extent, on the vegetative repro- 

 duction, seems to indicate that the species is not well adapted to the arctic 



1 Dikotyla jordstammar. (Acta TJn. Lund. XIX, 1882-83, p. 179.) 



