







344 



DB. F. BUCHANAN WHITE S 



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Viminalis, with triandra, cinerea, aurita, Caprea, repens, phyli- 

 cifolia, and purpurea. 



Lanata, with herbacea and reticulata. 



Lapponum, with cinerea, aurita, Caprea, nigricans, Arbuscula, 

 repens, Myrsinites, and herbacea. 



Myrsinites, with aurita, phylicifolia, nigricans, Arbuscula, Lap- 

 ponum, and herbacea. 



Serbacea, with aurita, phylicifolia, nigricans, Arbuscula, lanata 



Lapponum, Myrsinites, and reticulata. 



Reticulata, with nigricans, Arbuscula, lanata, and herbacea. 



Purpurea, with cinerea, aurita, Caprea, nigricans, Arbuscula, 

 repens, and viminalis. 



Whilst the foregoing list will serve to show the student what 

 hybrids may be expected to occur, the accompanying diagram 

 (Plate XI.) demonstrates the relation of both sections and species 

 as regards hybridization. The larger circles indicate the sections, 

 the smaller circles the species, and the lines connecting the 

 latter show that these hybridize. As regards Britain, both the 

 Pleiandrce and the Synandrce are lowland (i. e. not ascending 

 above 1000 feet) in their altitudinal distribution ; but the Diandra 

 include both lowland and alpine species ; and the groups thus 

 formed are indicated by dividing the circle by dotted lines and 

 numbering the segments. I. includes 8. viminalis only, which is 

 strictly lowland. II. forms a group of which the species, though 

 most common in the lowlands, ascend into the region of III., the 

 strictly alpine species, rarely, if ever, descending to 1000 feet. 

 IV., including S. Lapponum and S. Arbuscula, ought not perhaps 

 to be separated from III., since these are very rarely otherwise 

 than alpine in their distribution. 



Though nine or more ternary hybrids occur spontaneously in 

 Europe, none have been detected with absolute certainty in 

 Britain, perhaps from the great difficulty attending their re- 

 cognition. 



IV. Collecting. 



Since Willows produce their flowers either before the leaves or 

 when the leaves are only young, and since mature leaves are 

 necessary for the proper determination of the species, leaf- 

 specimens and flower-specimens cannot be obtained at the same 

 time ; hence, unless great care be taken, there is a real danger 

 that the flowers of one bush and the leaves of another mar he 

 taken to represent one specimen. 







































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