IRISH GARDENING 



A MONTHLY JOURNAL DEVOTED TO THE 

 \OLU.ME XI li ADVANCEMENT OF HORTICULTURE AND 



No. !44 



ARBORICULTURE IN IRELAND 



Editor J- W Besant 





Picea bicolort 



I'.\ l'i;<)i-i:ssoi; lii;M;v, M.A. 



NEW ' 



I'k'i:a nicui.oK is one ul: tin- rarest euiiifers in 

 cultivation. 'I'lie existence ot a. fine example 

 at (ilasnevin, which produced cones in 1917, 

 induces nie to give some account of this in- 

 teresting species. The genus Picea is divided 

 into two sections. In one section, to which 

 the common European spruce (Picea excelsa) 

 belongs, the needles are 4-sidecl, as is readily 

 seen when one is cut across, eacli of the sides 

 being marked with one or two white lines. In 

 the other section, to which the Sitka Spruce 

 (Picea sitchensis) belongs, the needles are 

 tiattened, presenting two surfaces, namely, a 

 convex green surface witliout any lines, and 

 a. Hat surface marked by two conspicuous white 

 bands, each band made up of six to eight 

 white lines. In Picea bicolor, wliicli is a spruce 

 with 4-sided needles, there is an attempt made, 

 so to speak, to combine the characters of both 

 sections. Two of the sides are green, each 

 having one or two lines, but the other two 

 sides are each marked with a white band of 

 six to eight lines. At first sight, then, Picea 

 bicolor looks like a flat leaved sj)ruce, as its 

 leaves seem to have a gi'een surface and a 

 white surface; but on closer examination tlie 

 4-sided character of each needle is apparent. 

 'Hiis species is unique in the gemis in tliis 

 [)eculiarity of the leaves. 



Picea bicolor is also peculiar in the extreme 

 variability in the amount of i)ubescence on the 

 twigs. In young trees all the twigs are quite 

 glal)rous, there not being tlie trace of a single 

 hail'. In older trees, the main twigs are often 

 covered M'itli minute hairs while the lateral 

 twigs remain glabrous. In other spruces the 

 presence of absence of hairs on the twigs is a 

 definite characteristic of the species, being 



uniform on all the twigs and in all ages of an 

 individual tree. The white si)ruce (Picea alba) 

 for example is quite hairless througlujut its life 

 on all its twigs; wliile the black spruce (Picea 

 nigra) has all its twigs hairy from early youth 

 to old age. This variation in tlie pubescence 

 of the twigs of Pi(;ea bicolor is ditiicult to ex- 

 plain; and deserves further study. In Japan 

 where the species occurs in a wild state on 

 many of the high mountains of Central Hondo, 

 but nowhere connnon, the leaves are also 

 variable in size and shape, being short (i-inch) 

 and very sharp-])ointed in yomig trees ; and 

 longer (J-inch) and bhmt pointed on old trees. 



The cones, which are about 3 inches long, 

 and somewhat similar in appearance to those 

 of the common spruce, are also extremely vari- 

 able in the shape of the scales, which are 

 obovate to rhombic, appressed or more or less 

 reflexed at the point, which is bi-oad and 

 rounded or narrowed, usually with a hiul,\' 

 toothed margin. 



Owing to tlie variation in the leaves and 

 cones, certain varieties (reflexa and acicularis) 

 have been distinguished by the Ja])anese 

 botanists Shirasawa and Koyama, but E. H. 

 Wilson believes that " these variations have no 

 taxonomic value," and I am inclined to agree 

 with his opinion. Picea bicolor is again re- 

 markable on account of the different names 

 which have been given to the s])ecies. It was 

 oi'iginally discovered by J. (i. Veitch in 1860, 

 who intended it to be named after Sir Ruther- 

 ford -Vlcock, the British Minister at I\)kio. 

 Unfortimately, the species which he sent home 

 were mixed witli those of another species, and 

 Lindleys name "Abies Alcoquiana," was ac- 

 companied by a description of the leaves of 



