336 



COVILLE 



Patterson's Checklist in 1892 omitted Salix polaris. Our material, 

 however, though fragmentary and unsatisfactory, makes it probable 

 that the species should again be considered a member of the North 

 American flora. Dr. Rydberg has already taken this view by identi- 

 fying Mr. Macoun's Cape Vancouver specimen as Salix folaris. 



21. SALIX PHLEBOPHYLLA Anders. 



Skeleton Willow. 



2 : 301. t. 10. 



Salix buxifolia Trev. ; Trautv. Nouv. Mem. Soc. Nat. Mosc. 



1832, not SCHLEICH. 181 5. 



Salix arc tic a minor Ledeb. F1. Ross. 3: 619. 1849-51, not Salix arbuscula 



mijtor 'Lk^st . 1845. 

 Salix phlebophylla Anders. Oefv. Kongl. Vet. Akad. Foerh. 15 : 131. 1858. 

 Salix palaeoneura Rydberg, Bull. N. Y. Bot. Gard. i : 267. 1899. 



A handsome little willow growing in mats on the ground, well dis- 

 tinguished from other Alaskan willows by the characters given in the 

 key. As in leiocarpa^ the bright green leaves are covered on both 



surfaces with minute light-colored dots, 

 visible under a lens, each of which marks 

 the position of a breathing pore. The 

 ovaries and capsules are usually pubescent, 

 though sometimes specimens are found in 

 which nearly the whole surface is entirely 

 smooth. The venation of the leaves is strik- 

 ing. On each side of the midrib are from 

 3 to. 6 conspicuous nerves nearly parallel 

 with the margin but running into it toward 

 the apex. These principal nerves are con- 

 nected with each other by several cross nerves. 

 After the growing season the leaves die but 

 remain attached to the stems, the tissue be- 

 tween the nerves of the leaf becoming trans- 

 lucent, and by the third season waste away, leaving the skeletonized 

 framework to clothe and protect the stems for several years. In 

 leiocarpa the nerves are equally conspicuous but the leaves are not 

 very persistent after the second season and they do not so regularly 

 become skeletonized. The stems of phlebophylla are stouter than 

 those of leiocarpa^ are less completely imbedded in the soil, and do not 

 so often form stolons. The plant grows on the tundra, and occurs 

 along probably the whole Arctic coast of Alaska from the British 

 boundary to Kotzebue and Norton sounds. 

 Specimens examined. 

 Siberian coast. — On Kayne, or Arakamtchechene, Island, collected 



Fig. 28. Salix phlebo- 

 phylla Anders. : «, fruiting 

 catkin, natural size ; b, pis- 

 tillate flower, enlarged six 

 diameters ; c, leaf, natural 

 size ; </, old leaf, skeleton- 

 ized, natural size. 



