1921] SCHNEIDER, NOTES ON AMERICAN WILLOWS, XII. 109 



Folia etiam matura subtus vix reticulata sed elevato-nervata. 



Stipulae pleraeque evolutae; ramuli hornotini densissime albo- 

 sericeo-villosi; folia 1.5:0.5 ad 3.5:0.9-1 cm. magna; species arctica 

 satis imperfecte cognita 42. 8. niphoclada. 



Stipulae pleraeque nullae vel minimae; ramuli hornotini vel saepis- 

 sime tantum novelli minus dense griseo- vel subflavescenti-sericeo- 

 villosi; folia ad 2.5-3:(0.6-)l vel 3.4:0.8 vel ad 3:1.1 cm. magna. 



41. S. brachycarpa. 

 Basis foliorum acuta vel sensim attenuata; folia ad ultra 10-plo longiora 

 quam lata; stipulae nullae vel in ramulis vegetis distinctae. 



94. S. tristis. 



Pubescentia foliorum saltern novellorum pilis ferrugineis griseisque mixta; 



species valde incomplete cognita mexicana 115. S. carta. 



b. Folia distincte petiolata petiolis 3-20 mm. longis instructa. 



1. Petioli versus apicem (vel basis laminae) glandulis distinctis saepe irregu- 



lariter lobulatis praediti; folia plusminusve dense glanduloso-denticu- 

 lata serratave. 



Folia matura subtus distincte albescentia vel glaucescentia. 



Laminae elliptico-lanceolatae, apice acutae, vix ultra 9:2.8 cm. magnae, superne 



estomatiferae . . . 5. S. serissima. 



Laminae apice plusminusve acuminatae vel caudatae, ad 16:4 vel 19:2.5 cm. 

 magnae, superne estomatiferae vel stomatibus paucis instructae. 



6. S. lasiandra. 

 Folia subtus concoloria viridescentia (interdum pallide viridia sed non glauces- 

 centia). 



Laminae utrinque aequaliter stomatiferae, plusminusve lanceolatae et sensim 

 caudato-acuminatae, pleraeque 4-5-plo longiores quam latae. 



6c. S. lasiandra var. caudata. 



Laminae superne haud vel sparse stomatiferae vel late ovatae, ellipticae vel 

 elliptico-lanceolatae et semper plusminusve subito caudato-acuminatae 

 vel haud ultra 3-plo longiores quam latae (in /. angustifolia 5-6-plo longiores 

 quam latae iis S. lasiandrae caudatae saepe similes sed basim versus magis 

 angustatae 7. 8. lucida. 



2. Petioli (vel basis laminae) eglandulosi} 



a Hamuli hornotini annotinique distincte pruinosi. 2 



Folia (novella saepe excepta) glaberrima, 3 anguste lanceolata vel plusminusve 

 oblanceolata, apice acuta, basi saepe obtuse cuneata, superne vivide viridia, 

 estomatifera, subtus albescentia, plusminusve distanter glanduloso-denticulata, 



4.5:0.9 ad ultra 10:2 cm. magna 64. S. irrorata. 



Folia semper (saltern subtus) tomentosa vel sericea. 



Stipulae distinctae, lineari-lanceolatae, ad 22:2 mm. magnae; folia obovato- 



vel elliptico-oblonga vel late lanceolata, 4.5:1.5 ad 10 : 3.2 cm. (vel ultra) 



magna, integerrima, subtus tomento densissimo opaco albo vel flavescente 



molli vestita costa saepe glabrescente prominula . 81b. S. alaxensis longistylis. 



Stipulae nullae vel parvae vel folia haud integerrima. 



Pubescentia pilis adpressis sericeis argenteis fulvisque mixta; folia parva, 

 anguste lanceolata, integerrima, utrinque acuta, 3:0.6 ad 7:1.8 cm. magna, 

 interdum subglabrescentia sed pilis adpressis tenuissimis difficila recog- 

 noscentibus semper plusminusve obtecta vel pulchre argenteo-sericea. 



85. S. Geyeriana. 



1 Small inconspicuous glands may be observed in S. B 'onplandiana , S. laevigata, 

 S. longipes and sometimes also in S. amygdaloides. 



2 The species of which the one year old (or older) branchlets, sometimes even the 

 young shoots are more or less covered with a glaucous bloom are mentioned again 

 later because the bloom may not always be present or sufficiently distinct. 



3 Of 102. S. planifolia the twigs are sometimes pruinose. Its leaves are lanceolate 

 to oboyate-oblong, entire or only partly denticulate and measure from 2:07 to 5:1.5-2 

 cm. See also 104a. S. pdlitam psilam the leaves of which are mostly linear-lanceolate 

 with a subrevolute and subcrenulate margin, and a very close nervation beneath. 



