4 BTJLLETIlSr 1050, V. S. DEPAETMENT OF AGRICULTURE. 



I. Wood light to dark reddish brown — Continued. 



B. Pores do not contain a reddish gum — Continued. 



1. Pores readily visible, etc. — Continued. 



BB. No white tangential lines consisting of rows of ducts, 

 but numerous very fine continuous lighter-colored lines 

 of soft tissue present, 120 to 175 per inch of radius, 

 barely visible without a magnifying glass. Wood 

 moderately heavy. 

 "Colombian mahogany" {Carimana pyriformis). 



CC. No fine light-colored tangential lines present ; struc- 

 ture very homogeneous. Color light purplish brown. 

 Wood moderately light and soft. 

 " Liberville mahogany " (Bostoellia klaincana) . 



2. Pores not readily visible without a lens. 



AA. Pores barely visible without a lens on smoothly cut sur- 

 faces in good light ; very distinct under a lens. The 

 heartwood is dull reddish brown ; the wide sapwood is 

 white. The wood is heavy, usually straight-grained. 



Sweet birch [Betula leoita). 



Yellow birch {Betula lutea). 



BB. Pores not visible without a lens; very small and uni- 

 formly distributed as seen with a lens. The heart- 

 wood is reddish brown, often with darker streaks; 

 the wide sapwood is pinkish white (unless blued by 

 stain). The wood is moderately heavy and usually 

 has interlocked grain. 

 Red gum {Liquidambar styraciflva) . 



II. Wood without reddish tinge. Color creamy white to yellowish brown. 



Growth rings sharply but not conspicuously defined by white tan- 

 gential lines or by a slightly darker band of summenvood. Pores 

 of practically uniform size throughout growth ring, barely visible 

 on a smoothly cut end surface, but very distinct as fine grooves on 

 planed longitudinal surfaces ; mostly filled with tyloses. Wood 

 with interlocked grain and moderately heavy. 

 "White mahogany," or prima vera (Tabebuia donnell-smifhii) . 



Note. — The sapwood of birch is without reddish tinge, and when taken by itself might 

 be classified under " II " above, although fresh cuts ai'e almost white. For means of 

 distinguishing birch from primavera, see descriptions of these species. 



DESCRIPTION OF SPECIES. 



TRUE MAHOGANY.^ 



Simetenia mahaffond Jacq.° ; Swietenia macrophylla King. ; Smietenia cirrTiata 

 Blake ; Stvietenia humilis Zucco. ; Sicietenia candollei Pittier. 



Mahogany Family (Meliace.e). 



other names. 



True mahogany comprises all the species of the botanical genus 

 /Swietenia, of which five are known at present.*' 



* See U. S. Dept. Agr. Bulletin 474, " True Mahogany," by C. D. Mell. For sale by 

 Superintendent of Documents, Government Printing Office, Washington, D. C. Price, 

 5 cents. 



6 The name after a scientific name is usually an abbreviation of the name of the person 

 who first described the species. 



9 Blaise, S. F., " Revision of the True Mahoganies." .Tournal of the Washington Acad- 

 emy of Sciences, vol. 10, pp. 286-207. f. 1-2. 



