CXCVIII. PLATANE^E. 679 



l-ovuled cells, the pendulous and anatropoua ovule, winged fruit, exalbuminous seed, and alternate 

 leaves with caducous stipules ; but their diclinisui and amentaceous inflorescence decidedly separate them. 



Betulacea are spread over the temperate and cold climates of the northern hemisphere. Birches form 

 woods or vast forests in Northern Europe, Asia, and America. Some stunted shrubs inhabit the polar 

 regions up to the limits of perpetual snow. Alders are dispersed over the temperate countries of the 

 northern hemisphere, and over sub-tropical America. 



The Betulacea, without rivalling Cupulifera in their use to mankind, furnish him with several 

 useful species, at the head of which must be placed the White Birch (Betula alba), which grows nearly 

 throughout Europe, Siberia, Asia Minor, and North America ; it approaches nearer to the pole than any 

 other European tree, and grows in alpine districts the least favourable to vegetation. Its wood is too 

 spongy to be employed in buildings, but cartwrights, upholsterers, and turners value it for its tenacity ; 

 as firewood it is nearly as useful as beech, and its charcoal is in demand for forges. Its flexible branches 

 are made into brooms. Its bark is impermeable to water, and hence used in the north for various 

 utensils, shoes, cords, boxes, snuff-boxes, and for preserving roofs from moisture. The bark of a variety 

 of the White Birch (the Canoe Birch or Paper Birch) is used in Canada for the construction of light and 

 portable canoes ; these are formed of sheets of bark bound together with the root-fibres of the White Fir, 

 and smeared with the resin of the Balsam Fir. The bark of the White Birch contains, besides an astrin- 

 gent principle used in tanning leather, a resinous balsamic oil, which becomes einpyreumatic by dis- 

 tillation, and is used in the preparation of Russia leather. Finally, the cellular part of this bark, which 

 contains starch, is a valuable resource to the Sanioiedes and the Kamtschatkans, who bruise it, and mix 

 it with their food. The sap, which is sugary before the sprouting of the leaves, is considered an excellent 

 antiscorbutic in North America, and both vinegar and beer are made from it. Other species of Birch 

 (.B. lenta, niyra, Itttea, &c.) are similarly prized in North America for their wood, tannin and sugary sap. 

 The common Alder (Alnus ylutinosa) is a nearly aquatic tree ; its wood is little used for buildings, 

 because it does not withstand alternate dryness and damp ; but if constantly submerged, it becomes aa 

 incorruptible as oak, whence its use for piles. Alder wood is used by upholsterers, cabinet-makers, 

 turners, and sabot-makers, and is esteemed for firewood, because it burns with a bright and almost 

 smokeless flame ; its charcoal is usually employed in gunpowder making. The bark, leaves, and cones 

 may be used for tanning and dyeing black. 



CXCVIII. PLATANE^E. 



, Lestiboudois. PLATANAOE^E, Lindl.) 



FLOWERS diclinous, in 1-sexual capitula. PERIANTH replaced by clavate scales. 

 STAMENS equal and alternate with the scales. OVARIES \-celled, 1-2-ovuled ; OVULE 

 pendulous, orthotropous. FRUIT a nut. SEED exalbuminous or not ; RADICLE inferior* 

 STEM woody. BUDS long, concealed by the concave base of the petiole, and only 

 appearing after the fall of the leaf. LEAVES stipulate, alternate, palminerved. 



Usually tall TREES, bark flaking. LEAVES alternate, petioled, palminerved, 

 large, few-lobed, furnished with stellate hairs, fugacious; stipules leaf-opposed, 

 tubular at the base, often crowned with a blade at the top, caducous. FLOWERS l 

 mono3cious, agglomerated in 1-sexual globose capitula, occupy ing different branches. 

 FLOWERS $ surrounded by scale-like bracts, minute, hairy at the top, and within 

 by sepals (arrested stamens?) longer than the bracts, linear-clavate, furrowed, truncate 

 at the top. STAMENS equal and alternate with the scales ; filaments very short ; 



1 [This description of tho and ? flowers of Plan- the arc mixed without definite order with scales 

 taneee does not accord with the usually received view, which may be bracts, perianth-segments, or staminodei, 

 which is, that tho stamens in the $ aud the ovaries in 0* arrested ovaries. 



