198 JOURNAL OF THE ARNOLD ARBORETUM [roL. ii 



Among the twenty-three sections enumerated by me in a later note 

 there are several groups peculiar to America and not represented in 

 the Old World; namely, Sect. Nigrae, Bonplandianae and Longifoliao. 

 Of the Nigrae the typical S. JI umholdtiana is restricted to South America, 

 probably ranging as far south as the Straits of Magellan, while its north- 

 ern representative, S. nigra, reaches the 50th degree N. Lat. in Ontario. 

 No other section covers such a wide area, as it is also found from the 

 Atlantic to the Pacific coast in California. 



The si)ccies of the Longifoliac, too, are widely spread from Guatemala 

 (S. taxifoUa microphylla) to the vicinity of Dawson in the Yukon Valley, 

 Yukon Territory (S. lomjifulia pcdiccUata) , and in the States from coast 

 to coast. 



The Bonplandianae inhabit a more restricted area from Guatemala 

 (S. Bonplandianae forma) to northern California (S. laevigata) or even 

 southern Oregon in the west, and Illinois to the Di^strict Columbia (S. 

 longipes Wardii) in the east. 



Other sections indigenous to Central and North America and apparently 

 of no distinct relation shij) to forms of the Old World are; Mexicanae 

 (tlu-ee species) in Mexico; Wolffianae (one species) in Idaho, Wyoming, 

 Montana, Oregon and Colorado. 



The Candidae with S. Candida (and possibly S. crypiodonta) are also 

 a section the true affinity of which is by no means clear. It is a Willow 

 of the northern United States from New Jersey to Montana, and of 

 Canada from Labrador to Allierta and probably to British Columbia and 

 the Great Slave Lake in the Northwest Territories. 



The Fulvae, too, with ^S. Behhiana, Geycriana and Lemmonii are a dis- 

 tinctly American group of wliich S. Behhiana is a widely spread member 

 from New Mexico to the Yukon Territory, and from Newfoundland and 

 New Jersey to northeastern Nevada and Washington. 



Very lijuited is the range of the strange Brewerianae (California), and 

 of the Sitchenses (Pacific coast from California to Southern Alaska). 



Other sections, like the Cordatae, Adenophyllae, Balsamiferae, Disco- 

 lores and Griseae, including only American forms, nevertheless show a 

 more or less distinct affinity to Asiatic and European species, while the 

 sections Reticulatac, Ovalifohae, Glaucae, Phyficifoliae, Chrysantheae 

 and Roscae combine species of the Old and New World. 



On the following pages I give an alphabetic enumeration of the species 

 met with in the different states of the United States and of Canada as 

 well as in Mexico and South America. Those species indigenous to or 

 hitherto known only from one state or district are marked with an asterisk. 

 A question-mark signifies that the occurrence of the species or form in the 

 region is stilJ doubtful or that it is not yet clearly identified. 



