HARDWOOD RECORD 



I lio cell walls urp iiKiinlly quite tliiii niiil cuntnin n 

 9iii;;|.' iK'W .'I i'kiii|^to<l siniplp jiiti (Hlitlikc) (Fi({. -. «.p.). which 

 arc iiirnrinbly pnnillol to tho long iixiB of the wood fliwr. ThcKC 

 oi>cninKii in the ooll wnll arc nboiit hnlf nnci often much louRor thnn 

 the cell Is wiile. 



Woo<l-pareorh\-niii fibers (Plato I, w.p.f.) arc very numcrouit, nml, 

 as a rule, regularly ilistributotl throughout the annual ring, only 

 oern^iioonlly being arrangotl in irregular tangential lines within the 

 latr«(>o.l. They are always in eonlart with vessels anil pith rays with 

 whioh tliey communiratc through small round simple pits. Wherever 

 wooil paronrhyma filx-rs are in eontnct with vessels the pits are in tho 

 walls of the latter. The walls are, as a rule, rather thin and contain 

 numerous simple pits on the radial sides (Pig. 3, «. p.). Crystals of 

 'iileium oxniate, which occur .so abundantly in black walnut wood, 

 ire almost entirely wanting in the wood of butternut (Fig. 4, c). 



Pith rays (Plate I, p.r.), which vary from one to three rows of 

 ■I'lls in width, are chielly two cells wide, ami from a few to fifty or 

 more cells high. In outline these rays are often spntulntc (Fig. G). 

 I'ith-my cells vary considerably in length and width. Those near the 

 middle of the ray are from one to three times as long as wide (Fig. 

 7, r.c), while those in the upper and lower rows of the ray are 

 ••onsiderably larger and are usually elongated in the axial direction of 

 •he stem (Fig. 7, m.r.c). Pith-ray cells communicate with each 

 ■ ther through small, round, simple pits (Fig. 7, ». p.), which are 

 ospecially numerous where these cells bordor vcsuols and wood-parcn- 

 i-hyma fibers. Crystals of calcium oxalate are seldoni present in pith- 

 ray cells. 



California Wainut 



California walnut (Juglans californica Watson) (Plate III) grows 

 in the California coast region (from the Sacramento river to the San 

 Bernardino Mountains). 



Uses 



California walnut is used only locally, but it is well suited for cabi- 

 net making and for the other purposes for which black walnut is so 

 extensively used. The logs are rather small, however, and the supply 

 is limited and difficult of access, so that there is little chance for this 

 wood to become important commercially. 



Gross Characters 



The nearly white sapwood is usually quite thick, even in old trees, 

 containing from ten to fifteen annual rings of growth. The heart- 

 wood is dark brown, with a bluish tinge, and becomes almost black 

 when exposed to light. Air-dried wood has a specific gravity of .GZ 

 and a weight per cubic foot of approximately thirty-nine pounds. It 

 is very hard, tough, strong, very fine-grained and somewhat cross- 

 grained, splitting with difficulty, but is easily worked, and takes a 

 high finish and polish. This wood checks very little in seasoning, but 

 unless carefully handled it is apt to warp considerably. Its' dura- 

 bility in contact with the soil is equal to that of the black walnut. 

 The largest trees have a diameter of from fifteen to twenty inches, 

 but usually not more than from ten to twelve inches, with a height of 

 from forty to sixty feet. 



California walnut resembles the wood of Mexican walnut, but is 

 readily distinguished from it by its more numerous pores and more 

 dJstinet tangential lines of wood-parenchyma fibers. 

 AIiNUTE Characters 



"Vessels (Plate III, r.) vary from 1.49 to 1.70 millimeters in diam- 

 eter, with an average of 1.14 millimeters (Table I). They are more 

 numerous in this than in any other native species and are generally 

 distributed singly in the earlywood, while in the latewood they often 

 occur in short radial rows of from two to five each. In outline they are 

 sometimes more or less irregular, particularly those near the outer 

 boundary of the annual ring of growth. The walls are usually very 

 thin and marked by numerous small bordered pits, which are arranged 

 in horizontal rovvs where they are in contact with other vessels, wood- 

 parenchyma cells, and pith-ray cells. The vessel segments are from 

 one to four times as long as the diameter of the vessels, and the parti- 

 tion walls between these segments (longitudinal section) are com- 

 pletely absorbed (simple perforations), leaving both ends of the seg- 

 ments open. 



Wood fibers (Plate III. w. f.) vary from .GJ05 to 1.4175 millimeters 



in length, with an average of 1.05(1 milllmelcra (Tnbl« II), which ii 

 much shorter thnn that of black walnut (Table III). These fibers 

 are arranged chielly in regular radial rows lietwern tho pithraj-s, and 

 they have thick walls and small cell cavities; in fact, the last five or lix 

 rows of wood fibers formed at the end of the growing sonaon havo cell 

 cavities that are almost entirely obscured. Simple, Klit-tike piti occur 

 on the radial walls arranged in a single row. 



Wood-parenchymn fibers (Plate III, w.p.f.) are more abundant in 

 this wood than in any other of the walnuts, frequently forming more or 

 less distinct tangential bands extending from left to right in the outer 

 portion of the annual ring. The walls are usually very thin and contain 

 numurous simple pits whore they are in contact with other wood-par 

 enchyma fibers and pithray cells. Tho pits are particularly abundant 

 in the cross-walls of the cells composing the fibers. Crystals of cnl 

 cium oxalate and calcium carbonate are found very sparingly in the 

 ivood of this species. 



Pith-rays (Plate III, p. r.) are from one to three cells wide, chiefly 

 only one cell wide, and from a few to 25 cells high (tangential section) 

 and spindle shaped in outline. The individual pith-ray cells (Fig. 

 7, r. c.) vary in length and width ; those near the middle of the rays are 

 long and narrow, while those in the upper and lower rows are polyg 

 onal or often elongated in the axial direction of the wood fibers (Fig. 

 7, m. r. c). Pith-ray cells have small simple pits, which are especially 

 numerous where the rays are in contact with vessels, as they are also 

 In the cross-walls of the individual ray cells. 

 Mexican Walnut 



.Mexican walnut (Juglanx ritjustri.i Engelmann) (Plate IV) grows 



in central Texas (Colorado, Llano, and Guadaloupe rivers) westward 



through southern New Mexico and Arizona and southward into Mexico. 



Uses 



The wood of this species Is little known to consumers of walnut, and 

 chiefly because of the small size and limited distribution of the tree 

 in a mountain region difficult of access. The rich dark brown color 

 of Mexican walnut, however, renders it valuable for practically all the 

 uses to which black walnut is put. While the small supply of the 

 timber available is sure to prevent general commercial use of this 

 wood, it should, nevertheless, become locally useful for cabinet work, 

 particularly in view of the high market price of black walnut. Mexi- 

 can walnut is now used by settlers mainly for fence posts and to a 

 limited extent for general building purposes. 

 Gross Characters 



The sapwood is nearly white and varies in thickness from ten to 

 twenty or more annual rings of growth, depending upon the age of 

 the tree. The heartwood Is dark brown or almost black. It Is the 

 heaviest of our native walnut woods, when air-dried having a specific 

 gravity of .68 and a weight per cubic foot of approximately forty-three 

 pounds. It is very hard, tough (splitting less easily than black walnut 

 and butternut), strong, and fine grained. In seasoning it checks and 

 warps but little, is easily worked, and takes a high finish and polish. 

 Its durability in contact with the soil is somewhat less than that of 

 black walnut. 



Mexican walnut is rarely over two feet in diameter, although occa- 

 sionally becoming five feet, with a height of from 50 to 60 feet. They 

 attain their greatest size in the mountain canyons of jn'ow Mexico and 

 Arizona. 



Minute Characters 



Vessels (Plate IV, v.) vary from .00.38 millimeter (Table I), being 

 easily seen with a pocket lens magnifying from four to six diameters. 

 They are more or less evenly distributed throughout the wood, either 

 singly or, less often, in short radial rows of from two to five, and are 

 surrounded by tracheids and wood-parenchyma fibers, which are slightly 

 greater in diameter than the average width of the wood fibers. The 

 walls and vessels are usually quite thin, especially those of solitary 

 vessels. The vessel segments (Fig. 1, v.s.) (to be seen only with the 

 qid of a compound microscope in longitudinal sections of the wood 

 or in macerated material) are usually short, seldom longer than the 

 vessel is wide. The partition walls between these segments are whoUy 

 absorbed, leaving the end of the segments open. In small vessels the 

 partition walls are often horizontal (longitudinal section), while in 

 large vessels they are more or less oblique, with elongated, pointed 



