IAWA Bulletin n.s., Vol. 10 (1),1989: 5-26
WOOD ANATOMY OF ELM (ULMUS) AND HACKBERRY (CELTIS) SPECIES NATIVE TO THE UNITED STATES1
by
E. A. Wheeler 2, C. A. LaPasha 2 and R. B. Miller3
Summary Wood anatomy of Ulmus and Celtis spe Core et al. 1979; Panshin & De Zeeuw 1980; cies (Ulmaceae) native to the United States is Constantine 1975; Hoadley 1980; Furuno described. Ulmus differs from ring-porous 1985), but complete wood anatomical de species of Celtis in ray structure, crystalloca scriptions of some species are lacking. The tion, and colour and fluorescence of water major purpose of this paper is to provide de extracts. The soft elms/non-winged bark tailed descriptions of the wood anatomy of species (Ulmus americana and Ulmus rubra) Ulmus and Celtis native to the United States. differ from the hard elms/winged bark spe Such infonnation will help with the identifi cies (U. alata, U. crassifolia, U. serotina, cation of isolated wood samples, both recent and U. thomasii) in density, earlywood pore and fossil. diameter, and appearance of crystal-contain ing axial parenchyma. Some species of hard Ulmus-Celtis comparison elm can be distinguished from one another by All species of North American Ulmus are a combination of characters: water extract col described as ring-porous; some species of our and fluorescence, earlywood pore diam Celtis are diffuse-porous, some are ring eter and spacing. The anatomy of ring-porous porous. Ring-porous species of Celtis can be species of Celtis is unifonn, except that in C. distinguished from Ulmus primarily by ray reticulata earlywood pores have a smaller ra structure (Pan shin & De Zeeuw 1980; Core dial diameter than the other species. Celtis et al. 1979; Jane 1970; and Metcalfe & Chalk pallida is diffuse-porous and resembles other 1950). Rays of Ulmus are predominantly diffuse-porous species of the genus. Vessel homocellular and mostly 3-5 cells wide; element lengths are similar for all species multi seriate rays of Celtis often are hetero within these two genera regardless of habitat. cellular with one to a few rows of square Key words: Wood anatomy, wood identi- and/or upright cells and mostly 5-8 cells fication, Ulmus, Celtis, Ulmaceae, elm, wide. hackberry. Sweitzer (1971) in a comprehensive study of wood and leaf anatomy of the Ulmaceae Introduction examined many species of both Ulmus and Species of elm (Ulmus L.) and hackberry Celtis from around the world. His emphasis (Celtis L.) have long been important timber was on generic and familial relationships and trees and ornamentals. Descriptions and/or not on species differences, and he examined illustrations of the wood of the commercially only one to three samples of each species. He important species of the United States have did not mention any species differences with appeared in a number of publications (e. g., in Ulmus, but did note, as Cox did earlier
1) Paper No. 11678 of the Journal Series of the North Carolina Agricultural Research Service, Raleigh, N.C. 27695-7643, U.S.A. 2) Department of Wood and Paper Science, Box 8005, North Carolina State University, Raleigh, N.C. 27695-8005, U.S.A. 3) Center for Wood Anatomy, Forest Products Laboratory, One Gifford Pinchot Drive, Madi son, WI, 53705-2398, U.S.A.
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(1941), that Celtis may be divided into two ferent sections of the genus Ulmus. Ulmus groups based upon pore distribution. Tem alata and U. thomasii belong to the Section perate species are ring-porous with vessels in Chaetoptelea, U. crassifolia to the Section wavy tangential bands (a feature described in Microptelea, and U. serotina to the Section the literature as ulmiform) and spiral thicken Trichoptelea (Elias 1970). One of the objec ings on the walls of the small vessel ele tives of this study was to determine if there ments; subtropical and tropical species are were any wood anatomical differences be diffuse-porous and lack wavy tangential tween these four species of hard elms. bands of vessels and spiral thickenings. Celtis Ulmus Six species of Celtis that reach tree size Six species of elm are native to North are native to North America. Only Celtis oc America: Ulmus americana L. (American elm), cidentalis L. (hackberry) and C. laevigata U. rubra Muhl. (slippery elm), U. thomasii Willd. (sugarberry) are commercially impor Sarg. (rock elm), U. alata Michx. (winged tant and both are native to the eastern United elm), U. serotina Sarg. (September elm), and States. Celtis reticulata Torr. (netleaf hack U. crassifolia Nutt. (cedar elm). In the wood berry) is a small irregularly shaped tree of the industry, American elm and slippery elm are western and southwestern United States; C. known as soft elms and the last four species lindheimeri Engelm. ex K. Koch (Lindheimer are known collectively as hard elms. The hackberry) is a small tree with stout spread terms soft elm and hard elm were coined ing branches restricted to the Edwards Pla because the soft elms have a lower specific teau in central and southern Texas; C. tenui gravity than the hard elms. The branchlets of folia Nutt. is a shrub or small, scraggly, tree the hard elms often have corky wings, those of eastern, midwestern, and southeastern of the soft elms do not, and so the hard elms United States; C. pallida Torr. (spiny hack are also referred to as winged-bark elms. All berry) is a spiny, densely branched shrub to North American elm species are deciduous. small tree of the southwest United States and According to Pan shin and De Zeeuw Mexico (Elias 1980). The wood anatomy of (1980), Core et al. (1979), Jane (1970) and these last four species previously has not others, American elm, slippery elm and the been illustrated or described in detail. Celtis hard elms can be distinguished from one an pallida is evergreen, while all the other spe other by earlywood characteristics. Slippery cies are deciduous. elm has an earlywood zone which is 2-4 pores deep composed of solitary pores and pore multiples, and the earlywood pores are Materials and Methods visible to the naked eye. American elm has a Mature wood specimens were obtained single near-continuous row of solitary early from the Bailey-Wetmore Laboratory of Plant wood pores which are visible to the naked Anatomy and Morphology (Aw) of Harvard eye. The hard elms have a single discontin University, Cambridge, Massachusetts; the uous row of small, widely spaced earlywood Samuel J. Record Collection (SJRw) and the pores which are barely or not visible to USDA Forest Products Laboratory Wood the naked eye. Jane (1970) noted that the Collection (MADw) of Madison, Wisconsin, hard elms could barely qualify as being ring and the David A. Kribs wood collections at porous because the solitary earlywood pores North Carolina State University (PACw), are small and the wavy tangential-diagonal Raleigh, North Carolina. Many of the sam bands of small pores extend from the late ples were collected as part of Project I of wood into the early wood. Pan shin and De the State University of New York, Syracuse, Zeeuw (1980) and Core et al. (1979) do not New York; the Project I samples used were distinguish wood of any of the four species from the D.A. Kribs collection, but the xyla of hard elm from one another. These four riorum numbers cited are Syracuse wood species of hard elm, all of which are winged numbers (BWCw). Some of the samples are bark elms, have been assigned to three dif- from Sargent's Tenth Census woods; they are
Downloaded from Brill.com10/06/2021 12:53:49PM via free access Wheeler, LaPasha & Miller- Wood anatomy of Ulmus and Celtis in the U.S.A. 7 cited by their PACw number, as well as the 6268: MO, Letterman, US 233-134 - PACw Tenth Census designation (e.g., 223-101). 6269: VT, Pringle, US 233-366 - PACw The samples examined are listed below by 6270: VT, US 233-369 - PACw 6271: species. Information is given in this order: MASS, Robinson, US 233-869. xylariorum number, state, collector, location Ulmus serotina (5 samples) - BWCw of herbarium vouchers if known. 8474: TENN, L.E. McCormick, US, A - Ulmus alata (15 samples) - BWCw 8218: Aw 20651: ILL, R. Ridgeway 890 - Aw LA, Bickford, US, A - BWCw 8369: FLA, 33267: MASS, Cult. AA 17927-B - MADw Antone, US, A - BWCw 8635: GA, Bishop, 19329: MISS, T. Bouler, MAD - MADw US, A - PACw 3408: MO - PACw 6281: 11028: MISS, T. Bouler, MAD. SC, Ravenel, US 226-133 - PACw 6282: Ulmus thomasii (14 samples) - BWCw TENN, Gattinger, US 226-380 - PACw 8016: NY, H.P. Brown, US, A - BWCw 6283: MISS, Mohr, US 226-533 - MADw 8024: NY, H.P. Brown, US, A - BWCw 2121: GA, Akerman - MADw 2122: MO, 8153: MICH, B. Spike, US, A - BWCw Koehler - MADw 2126: TEX, Pond - 8481: MINN, L.W. Rees, US, A - PACw MADw 2128: ARK, Koehler - MADw 3411 - PACw 6279: MICH, W.J. Beal, US 10068: LA, Baudendistel - MADw 10069: 225-1163 - PACw 6280: MICH, W.J. Beal, LA, Baudendistel - MADw 10071: TEX, US 225-314 - MADw 2123: WI, A.K. Arm Baudendistel - MADw 19446: MISS, strong - MADw 2124: WI, A.K. Armstrong Bouler. - MADw 2127: WI, A.K. Armstrong - Ulmus americana (10 samples) - BWCw MADw 6491: IN - MADw 7228: MICH, 8014: NY, H.P. Brown, US, A - BWCw B.H. Paul TI5 - MADw 7229: MICH, B.H. 8019: NY, F.M.CaIlward, US, A - BWCw Paul TI4 - MADw 7230: MICH, B.H. Paul 8429: FLA, J.B.McFarlin, US, A- BWCw TI2. 8595: WI, LH. Isenberg, US, A - PACw Celtis laevigata (11 samples) - BWCw 6272: MASS, Sargent, US 244-19 - PACw 8303: FLA, A. S. Rhoads, US, A - BWCw 6274: MO, Letterman, US 244-281-1 - 8423: TEX, E.D. Marshall, US, A - BWCw PACw 6275: MO, US 224-281-2 - PACw 8473: GA, G.N. Bishop, US, A - BWCw 6276: TEX, Mohr, US 224-958 - PACw 8690: TEX, B. C. Tharp, US, A - MADw 6277: MASS, Robinson, US 224-1036 - 2099: MO, A. Koehler - MADw 3404: MO PACw 6277: MASS, Robinson, US 224- - MADw 4704: MISS, Bordeaux - MADw 1049. 10061: MISS, Baudendistel- MADw 10076: Ulmus crassifolia (15 samples) - BWCw MISS, Baudendistel - MADw 35932: MO, 8559: ARK, W.L. Lear, US, A - BWCw H. H. Smith, F - MADw 35933: Mexico, 8680: MISS, H.H. Muntz, US, A - Aw A.F. Wilson M-17, MAD. 29887: MISS, J.T. Drow 43 - PACw 3409: Celtis lindheimeri (1 sample) - SJRw MO, H.H. Smith, F - PACw 6264: TEX, 40672: TEX, H. Nogle 764. Reverchon, US 222-324 - PACw 6265: Celtis occidentalis (10 samples) - BWCw Mohr - MADw 8474: LA, Paul & Marts., 8159: NY, H.P. Brown & C.c. Forsaith, MAD - MADw 8475: LA, Paul & Marts. - US, A - BWCw 8272: MO, Westvelt, US, A MADw 10065: LA, Baudendistel - MADw - BWCw 8496: WV, F. Johnson, US, A - 10666: TEX, Baudendistel- MADw 14376: PACw 6286: MO, Letterman, US 228-69- MISS, J. T. Drow 41, MAD - MADw PACw 6287: TEX, Reverchon, US 228-306 14381: MISS, J. T. Drow 48, MAD - - PACw 6288: TENN, Gattinger, US 228- MADw 35965: TEX, Nogle 162 - SJRw 375 - PACw 6289: MASS, Robinson, US 11927 -MADw 19391: MISS, T. Bouler. 228-864 - PACw 6290: MASS, Robinson, Ulmus rubra (9 samples) - BWCw 8015: US 228-873 - PACw 6291: MO, Eggert, US NY, H.P. Brown, US, A - BWCw 8167: 228-111- MADw 23597: ILL, R.W. Merz, PA, D.A. Kribs, US, A - BWCw 8482: MAD. MINN, L.W. Rees, US, A - PACw 6266: Celtis pal/ida (4 samples) - BWCw 8631: KY, W.M. Linney, US 223-301 - PACw TEX, B.C. Tharp, US, A - Aw 25844: 6267: VT, Pringle, US 233-101 - PACw Mexico, I.M. Johnston-MADw 9927: J.L.
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Stearns CA108 - SJRw 14766: AZ, S.B. Careful focusing was necessary to ascertain Detweiler 41, MAD. whether or not perforations were present, es Celtis reticulata (12 samples) - BWCw pecially if the vessel elements happened to be 8449:WA, E.C. Jahn et aI., US, A-BWCw positioned so that the perforation was at the 8580: AZ, Johnson, US, A - BWCw 8667: side. Sometimes it was necessary to shift the UT, Tangren, US, A - Aw 20405: MA, cul cover slip to change the cell orientation. The tivated AA 4099-1 - A w: 25845: Mexico, relative percentages of vessel elements and l.M. Johnston - PACw 6292: AZ, Engelm. vascular tracheids was detennined by scan & Sargent, US 228-652 - MADw 13259: ning two different slide preparations and TEX, H. Nogle 1534 - MADw 15585: TEX, counting a minimum of 200 vessel elements Nogle-Wilson T-7, MAD - MADw 15608: and vascular tracheids. TEX, Nogle-Wilson T-36, MAD - SJRw Permanent slides already were available 14781: AZ, S.B. Detweiler 56, MAD - for some specimens, for others permanent SJRw 40228: TEX - SJRw 40576: ID, Proc slides were prepared by softening the wood tor 159. in boiling water, sectioning, and then staining Celtis tenuifolia (2 samples) - MADw with either safranin alone, or double staining 9841: GA, Stearns 1476 - MADw 14602: with safranin and hematoxylin. For vessel PA, Robacker, MAD. element diameter of the ring-porous species, 25 of the 'larger' earlywood vessel elements Vessel element lengths and relative per were measured, for the diffuse-porous Celtis centages of vessel elements and vascular pallida, both 25 randomly selected and 25 of tracheids were determined from macerations. the larger vessel diameters (Miller 1981) were Macerations were prepared by placing wood measured. The wall was included in the mea fragments in a solution of equal parts of 30% surement. Most of these measurements were hydrogen peroxide and glacial acetic acid and made by projecting the slide's image onto warming for 1-2 days in a 50° C oven. For a Graphics Tablet attached to an Apple lIe each sample, lengths of fifty vessel elements microcomputer. For the hard elms distances were measured; for some samples with wide between the outer walls of 25 solitary early growth rings, early wood and latewood were wood vessels were measured, and the mean macerated separately to determine if there distance between the early wood pores, as was a difference between early wood and late well as the maximum distance was deter wood vessel element lengths. Although fibre mined. For Celtis pallida vessel density and lengths are reported in the general descrip percentage of solitary pores were determined tions, fibre lengths were determined for only by counting each vessel, including those in a few samples of each species, and were not pore mUltiples, as an individual unit (Wheeler used in the statistical analyses. Fibre length 1986). Multiseriate ray heights were deter can vary considerably (as much as 100%) mined in two ways: 1) 25 rays chosen at within a growth ring, and the location of random were measured, and 2) 25 of the greatest fibre length within a growth ring larger rays were measured and the mean of varies between species (Taylor 1976; Panshin the ten largest was determined. The second & De Zeeuw 1980; Wilson & White 1986). method is that recommended in the 1981 Consequently, considerable sampling is re IA WA 'Standard List of Characters Suitable quired for obtaining the number of fibre for Computerized Hardwood Identification' length measurements that would permit valid (Miller 1981). statistical comparisons of different species. It Analysis of variance (ANDY A) for un did not seem appropriate for this study to balanced design was run separately on the invest the time in obtaining these data. Fibre Ulmus data and the Celtis data. Individual wall thickness descriptions follow Chattaway ANDY As were run for each of the measured (1932). characters using the character values as the Distinguishing between narrow vessel ele dependent variable and the species as the ments and vascular tracheids is not easy. class variable using the SAS (Statistical Anal-
Downloaded from Brill.com10/06/2021 12:53:49PM via free access ~ [ g
~ Il> '";:r 300 Il> ?J:> r ~ U I ~ ... I
It 200 [ ~ 200 300 I 'SOO !' t § o~ ttl t '00 "'''600 ~ t H t g, c:: 3" '00 '00 ft200 t,... fHt!.::: L""oo c t t VI 50 am th cr am Ih cr am th cr am Ih cr am th cr am th cr ! ru al se ru al se ru al se ru al se ru al se ru al se Q Downloaded fromBrill.com10/06/2021 12:53:49PM MTD MRD MYEL %VE MRH TRH Po '":; . S- Fig. 1. Comparison of selected quantitative characters of Ulmus americana (am), U. rubra (ru), U. thomasii (th), U. alata (al), U. crassifo o lia (cr), and U. serotina (se). MID = Mean tangential diameter of earlywood vessels. MRD = Mean radial diameter of earlywood vessels. c:: MVEL = Mean vessel element length. %VE = Per cent of tracheary elements that are vessel elements. MRH = Mean ray height of V) multi seriate rays. TRH = IA WA 'standard list' ray height, average of the ten largest of the 25 larger rays. For each species, the long thin :> line represents the total range of sample means, the rectangular area represents the species mean +/- one standard deviation; the short bar (middle of the rectangle) indicates the species mean. All of the values, except % VE, are in Ilm. via freeaccess \0 10 IAWA Bulletin n.s., Vol. 10 (1),1989
Figs. 2-9. Ulmus. 2-7: Transverse sections showing earlywood zones of differing depths, pore sizes, and spacing, and the latewood with 'ulmiforrn' pore arrangement - Fig. 2. U. americana. Relatively continuous row of large earlywood pores, earlywood zone one pore deep. BWCw 8014. - Fig. 3. U. rubra. Earlywood pore zone more than one pore deep. BWCw 8015. - Fig. 4. U. serotina. Single row of oval-shaped early wood pores, rather close spacing of early wood pores. BWCw 8474. - Fig. 5. U. thomasii. Discontinuous row of 'enlarged' solitary earlywood pores. BWCw 8016. - Fig. 6. U. alata. Discontinuous row of 'enlarged' solitary
Downloaded from Brill.com10/06/2021 12:53:49PM via free access Wheeler, LaPasha & Miller- Wood anatomy of Ulmus and Celtis in the U.S.A. 11 ysis System) procedure GLM (general linear Results models). The null hypothesis being tested Following are descriptions of the wood stated that there was no difference between anatomy of Ulmus, ring-porous Celtis, and the species means for a character. For a par the diffuse-porous Celtis pallida. Characters ticular character, if the probability of exceed not mentioned in the description, such as ing the F value derived from the ANDV A was canals, silica, rap hides, etc., are absent. A less than 0.001, then the null hypothesis was dichotomous key is presented in Appendix I rejected and a posteriori pairwise compari on page 21. sons of the species (class) means were made for this character using the GT2 (SMM) op Ulmus tion of the 'MEANS' statement in the SAS Table 1 summarises by species the charac procedure GLM. An alpha level of 0.001 was teristics of Ulmus wood. Figure I presents chosen for the ANDV As to minimise the prob selected quantitative data for Ulmus in graph ability of making type I errors (false rejection form. Characteristics of the species are illus of the null hypothesis) during the subsequent trated in Figures 2-19. pairwise t-tests. The pairwise comparisons Sapwood grayish white to light brown; are based on Hochberg's (1974) method heartwood light brown to brown or reddish using studentised maximum modulus and brown. Heartwood surfaces of most samples employing Sidak's (1967) uncorrelated-t in (15 of 19 examined) of U. rubra fluoresce equality. When used with unequal sample greenish yellow to pale yellow green. Heart sizes, this method holds the maximum ex wood of all other elm species is not fluo perimentwise error rate under complete or rescent. Colour and fluorescence of water partial null hypothesis at a level not exceeding extracts are variable (see Table 1). Alcohol alpha. An alpha level of 0.05 was used in extracts colourless, fluorescence generally these tests. A significant difference between a blue, except in U. rubra where it is often pair of species means indicates that, at the green. level of sampling used, the two groups can Growth rings distinct. Wood ring-porous, be statistically distinguished. The lack of a except in some samples of U. crassifolia significant difference, on the other hand, which have no distinct early wood pore ring does not imply that the groups are the same, of larger vessels; in a single row (U. ameri but only that the two groups cannot be cana and the hard elms) or in 2-5 rows distinguished statistically at the level of sam (Ulmus rubra); total range of mean tangential pling used for that character. diameters of earlywood vessels 62 (U. cras Colour and fluorescence of water and sifolia) to 237 ).tm (U. americana); transition alcohol extracts generally were determined to late wood generally abrupt, latewood ves as described by Miller (1981), with minor sels in wavy tangential to diagonal bands, modifications. Fluorescence of the water latewood vessels in clusters, and more rarely extract was determined after the wood chips in radial multiples; perforation plates exclu had been immersed in the pH 6.86 buffered sively simple; vessel elements short, range of water solution for 2 to 5 minutes, and then mean vessel element length 190 (U. crassi brought just to a boil. folia) to 327).tm (U. americana); alternate
earlywood pores. BWCw 8635. - Fig. 7. U. crassifolia. Widely spaced row of 'slightly enlarged' earlywood pores, wood almost not ring-porous. BWCw 8559. - Fig. 8. U. thomasU, growth ring boundary, showing marginal parenchyma and relatively few small diameter cells (vascular tracheids and parenchyma) associated with vessels. MADw 6491. - Fig. 9. U. alata, growth ring boundary with marginal parenchyma, small diameter cells associated with the vessels relatively abundant. BWCw 8635. - Scale bar = 1 rum in Figs. 2-7; 100).tm in Figs. 8&9.
Downloaded from Brill.com10/06/2021 12:53:49PM via free access Table 1. Comparison of selected characters of Ulmus. I N
Ulmus MTD Range MTD MRD Range MRD MVEL Range MYEL %YE Range %VE
americana 186 (26) 147 (21) - 237 (41) 243 (35) 192 (28) - 298 (47) 246 (37) 201 (37) - 327 (50) 91 (2) 87-94 rubra 193 (19) 161 (26) - 231 (38) 255 (37) 210 (24) - 331 (37) 227 (24) 191 (29) - 276 (50) 83 (5) 75-88 thomasij 143 (13) 125 (28) - 162 (28) 160 (23) 122 (24) - 207 (30) 247 (32) 191 (33) - 286 (39) 72 (8) 53-85 alata 124 (10) 112 (23) - 143 (28) 130 (16) 99 (22) - 162 (23) 227 (24) 196 (32) - 273 (32) 78 (5) 70-85 crassifolia 98 (14) 62 (13) - 118 (16) 108 (17) 78 (15) - 138 (20) 224 (24) 190 (35) - 251 (40) 64 (6) 56-73 serotina 125 (10) 115 (20) - 137 (23) 161 (33) 130 (33) - 201 (28) 208 (9) 196 (47) - 217 (29) 85 (3) 81 - 89
Mean Range MRH RangeMRH TRH RangeTRH RPMM Range Range Ulmus EWD MaxEWD RW
americana NA NA 262 (62) 183 (66) - 371 (158) 518 (149) 272 (12) - 739 (52) 5.4 (0.9) 4.1 - 7.4 1-5 (6) rubra NA NA 269 (34) 222 (92) - 342 (137) 507 (55) 404 (21) - 579 (78) 5.8 (1.\) 4.1-7.6 1-5 (6) thomasji 80 - 264 228 - 1183 264 (46) 211 (76) - 354 (168) 491 (119) 374 (28) - 781 (108) 5.6 (0.7) 3.4 - 6.6 1- 6 (7) alata 155 - 380 403 - 1301 293 (59) 168 (76) - 438 (208) 535 (100) 279 (22) - 710 (34) 6.5 (0.8) 5.5 - 8.3 1- 6 (7) crassifolia 165 - 854 525 - 3365 304 (61) 230 (86) - 446 (260) 622 (109) 511 (83) - 836 (104) 7.1 (0.8) 5.6 - 8.2 1-6 (8) serotina 89 - 185 395 - 799 251 (60) 187 (66) - 348 (142) 455 (123) 336 (82) - 618 (55) 7.2 (0.7) 6.6 - 8.3 1-7 .... :» Ulmus Crystals Warer Extract ~ Auorescence Water Extract :» americana + (1), - (9) Colourless to Downloaded fromBrill.com10/06/2021 12:53:49PM slight Blue Green rubra (6), - (4) Colourless-light Yellow e. + Green (> thomasii +c (1), -(17) Yellow ::to Blue Green, Blue, or Green Blue :l alata + (12), - (7) light Brown, light Yellow Brown, Red Brown, dark Red Brown Blue Green, Blue, or Green Blue :l crassifolia + (10), - (3) light Brown, light Yellow Brown, Red Brown, dark Red Brown Blue Green, Blue, or Green Blue serOlina + (4), (1) Colourless-light Brown 1" Blue Green, Blue, or Green Blue < ~ Legend: MTD =mean tangential diameter for the species; Range MID =range of mean tangential diameters of samples examined; MRD = mean radial diameter; VEL = vessel ele o ment length; % VE = per cent of tracheary elements that are vessel elements; EWD = distance between outer walls of enlarged earlywood vessels; Max EWD = range of maximum dis ~- tance between outer walls of enlarged earlywood vessels; MRH = mean multiseriate ray height; TRH = mean of the 10 tallest multi seriate rays (all of preceding values, except % YE - are in Ilm); RPMM = rays per millimetre; RW = ray width in cells; For MTD, Range MTD, MRD, Range MRD, MVEL, Range MVEL, %VE, MRH, Range MRH, and TRH via freeaccess 'D -00 the number in parentheses is the standard deviation. For rystals', + represents presence, - represents absence, and number in parentheses represents number samples, r = rare. 'C of 'D Wheeler, LaPasha & Miller - Wood anatomy of Ulmus and Celtis in the U. S.A. 13
Figs. 10-19. Ulmus. - Fig. 10. Crowded alternate intervascular pitting, U. americana, BWCw 8595. - Fig. II. Vessel-ray parenchyma pits, U. thamasii, BWCw 8024. - Fig. 12. Spiral thickenings in narrow vessel elements, U. rubra, BWCw 8167. - Fig. 13. Local storied struc ture of vessel elements and vascular tracheids, U. alata, BWCw 8635. - Fig. 14. Strand of inflated crystalliferous axial parenchyma, tangential view, U. seratina, BWCw 8474. - Fig. IS. Strand of inflated crystalliferous axial parenchyma, radial view, U. crassifalia, MADw 35966. - Fig. 16. Strand of crystalliferous parenchyma, not inflated, radial view, U. rubra, BWCw 8015. - Fig. 17. Tangential section of U. thamasii, BWCw 8481. - Fig. 18. Tangential section of U. americana, BWCw 8014. - Fig. 19. Tangential section of U. thamasii, BWCw 8481. Scale bar = 100 11m in Figs. 10, 13, 15-19; 50 11m in Figs. 11, 12, 14.
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intervascular pitting, non-vestured, medium-
~ 0,,",0 large (8-12 J.l.m), generally crowded and if ~ "f "f ~ hexagonal in outline, pit apertures circular in ~ :2;;;;;:: ~ ~ ~ ~ outline; pits to axial and ray parenchyma es- il': § N N N sentially the same size as intervascular pitting ~ ~ ~ I il': although occasionally slightly larger, borders ~ e;.. c e;.. much reduced, with some pits appearing sim- if r::: te ;::: 1 ::E pie, often with pointed ends, and at times ::E :;:;:;:; ~ unilaterally compound. Narrow vessel ele- ....l ~ ~ ~ ~ I I I ments with spiral thickenings. Narrow vessel !.Ll ~ ~ ~ '" 0 t- 00 I· d· I h ·d ,....; > 00 ""' '" §
B() '"bO c-;'___ '7 c-;' ,@I-l-1 ~____ ~ 8:::!., &1.. ~c ~ c ~ c cheal, intermixed with the vascular tracheids, ~ § ~ C 8, ~ ;::) !;;: %l ~ ~ ~ ~nd surroundi.ng the ves~els, a!so marginal, .;:: il': ""' ... t; ""' ... ~ eI eI eI In some speCIes short dIscontInuous bands _ 00 Vi <''1 ...... E-< il': ~___ &:l ~ 'I il': ~ViC"lI,Q ~ ~ I as viewed in tangential section. Occasional ~ g) ~ ;::;- CO M local storied arrangement of vessel elements, ~ 'j' 'j' 'j' vascular tracheids, and parenchyma in some ~ ~ ~ I ~ ~ ~ I t- 8-;;:;: 8- samples of all species. _..q-r- ::I: N-OO U -"-'- f3 ~ ~ ~ I il': B:; 2- I ':j:' + ':j:' Rays not storied, homocellular, composed ::E ~ ~ § I ::E ~:; 0: I exclusively of procumbent cells. Multiseriate ...... '" rays 2-6 cells wide, mostly 3-5, and rarely to 8 cells wide. Uniseriate rays common, low, rarely more than 10 cells high. Mean ~ <:j ~ <:j ~ <:j number of rays per mm 4-8. Mean multi- s-- s-~ _-- .!:; .g, ~ ~ .!:;.g, ~ ~ .!:;.g, ~ ~ seriate ray height ranges from 168 J.l.m to 446 -;: ~.<:;.~ -;: ~'<:;.g -;: ~.~.~ J.l.m; mean height of the 10 largest rays ranges " <:j <.> ~ " <:j <.> ~ " <:j ~ ~ '-' - "'... '-' - "'" '-' - '" " from 272 to 836 ~. Downloaded from Brill.com10/06/2021 12:53:49PM via free access Wheeler, LaPasha & Miller- Wood anatomy of Ulmus and Celtis in the U.S.A. 15 1200 300 1000 250 300 100 600 800 200 200 250 t 400 tt t 600 150 150 200 ttL f 200 I 400 la re la re la re la re la re la re oc oc oc oc oc oc MTD MRD MVEL %VE MRH TRH Fig. 20. Comparison of selected quantitative characters of Celtis laevigata (la), C. occidentalis (oc) , C. reticulata (re). For explanation see caption of Fig. 1. Ring-porous species of Celtis ray parenchyma essentially the same size as Table 2 summarises the quantitative fea intervascular pitting although occasionally tures of C. laevigata, C. occidentalis, and C. slightly larger, without prominent borders, reticulata. Figure 20 presents selected quan often with pointed ends, and at times uni titative data in graph form. Characteristics of laterally compound. Narrow vessel elements the ring-porous species of Celtis are illus with spiral thickenings and intergrading with trated in Figures 21-36. vascular tracheids with spiral thickenings and Sapwood grayish white to creamy light crowded alternate pits. Thin-walled tyloses brown; heartwood cream to yellowish gray. present in earlywood vessels of some sam Water and alcohol extracts colourless and ples. Vessel element walls 2-4}tm when not non-fluorescent. in contact with other vessels, single wall Growth rings distinct. Wood ring-porous, thickness of vessels in multiples is 4-7 }tm. earlywood pores in 2-4 continuous rows. Fibres non septate, pits rare and without Total range of mean tangential diameters of obvious borders. Sample mean fibre lengths the solitary earlywood vessels 105 }tm (C. of 1090 (s.d. = 179) to 1167 (s.d. = 140) reticulata) to 229 }tm (C. occidentalis), mean }tm; thin to thick-walled. radial diameters from 127 }tm (c. reticulata) Axial parenchyma predominantly paratra to 303 }tm (C. occidentalis); earlywood to cheal, intermixed with the vascular tracheids, latewood transition abrupt when growth rings also marginal. Parenchyma strands generally are relatively narrow, and more gradual when of 4 cells, occasionally 2 cells. growth rings are wider. Latewood pores in Rays not storied, multiseriate rays homo wavy tangential to diagonal bands, vessels in cellular and heterocellular within the same clusters, and more rarely in radial multiples; sample, heterocellular rays generally with one perforation plates exclusively simple; vessel marginal row of square and/or slightly up elements short, range of mean vessel element right cells, occasionally more rows (up to 6). lengths 176 }tm to 286 11m (both in C. reti Multiseriate rays commonly up to 10 cells culata); alternate intervascular pitting, non wide, often to 12, rarely to 15 cells wide (one vestured, medium-large (8-12 }tm), general sample of C. laevigata, BWCw 8303). Un i ly crowded and hexagonal in outline, pit seriate rays common, low, rarely over 10 apertures circular in outline; pits to axial and cells high. At times, rays tending to be of two Downloaded from Brill.com10/06/2021 12:53:49PM via free access 16 IAWA Bulletin n.s., Vol. 10 (1),1989 Figs. 21-26. Celtis, transverse sections. - Fig. 21. C. laevigata, MADw 35932. - Fig. 22. C. tenuifolia, MADw 14602. - Fig. 23. C. lindheimeri, SJRw 40672. - Figs. 24-26. C. reticu lata, transverse sections. - Fig. 24. SJRw 40228, relatively wide growth ring with gradual tran sition from earlywood to latewood. - Fig. 25. A w 20405, narrower growth rings than Fig. 24 and more abrupt transition from early wood to latewood. - Fig. 26. BWCw 8667, narrow growth rings and abrupt transition from earlywood to latewood; earlywood vessels with tangen tial diameter greater than radial diameter. Scale bar = 250 J.1.m. Downloaded from Brill.com10/06/2021 12:53:49PM via free access Wheeler, LaPasha & Miller- Wood anatomy of Ulmus and Celtis in the U.S.A. 17 Figs. 27-36. Celtis. - Fig. 27. C. laevigata, spiral thickenings and simple perforation plates, BWCw 8690. - Fig. 28. C. occidentalis, crowded alternate intervascular pitting, BWCw 8496. - Fig. 29. Vessel-parenchyma pits in C. reticu!ata, PACw 6292. - Fig. 30. C. laevigata, crys tals in ray parenchyma cells, BWCw 8690. - Fig. 31. C. reticulata, tangential section, crystals in ray parenchyma cells at sides of rays, and at margins, BWCw 8580. - Fig. 32. C. reticulata, crystals in ray parenchyma cells at side of ray (position of sheath cells) cross section, PACw 6292. - Figs. 33-36. Tangential sections of Celtis. - Fig. 33. C. laevigata, note parenchyma strands of 4 cells, BWCw 8473. - Fig. 34. C. laevigata, BWCw 8368. - Fig. 35. C. reticulata, BWCw 8580. - Fig. 36. C. tenuifolia, MADw 14602. - Scale bar = 100 ).tm in Figs. 27, 30- 36; 50).lffi in Figs. 28 & 29. Downloaded from Brill.com10/06/2021 12:53:49PM via free access 18 IAWA Bulletin n.s., Vol. 10 (1),1989 Figs. 37-40. Celtis pallida. - Fig. 37. Transverse section, BWCw 8631. - Fig. 38. Transverse section, Aw 25844. - Fig. 39. Radial section, BWCw 8631. - Fig. 40. Tangential section, showing parenchyma strands, intervascular pitting, and inclination of vessel element end wall s, BWCw 8631. - Scale bar = 250 jlm in Fig. 37; 100 jlm in Figs. 38 & 40; 50 jlm in Fig. 39. sizes, uniseriate and biseriate rays common largest rays from 447-1145 11m. Crystals with very few 3-4 cell wide rays, and more present in the ray cells, none observed in 6-10 cell wide rays. Mean number of rays axial parenchyma. Crystals of sporadic oc per mm 3 to 7. Mean of the multi seriate ray currence, present in some samples, absent in heights ranging from 206 jlm to 719 jlm others, most frequently in the uniseriate rays, (both in C. reticulata); mean height of the 10 and in the marginal cells or cells at the sides Downloaded from Brill.com10/06/2021 12:53:49PM via free access Wheeler, LaPasha & Miller- Wood anatomy of Ulmus and Celtis in the U.S.A. 19 of the rays (position of sheath cells) in multi rays in Ulmus are homocellular and typically seriate rays; not uniformly distributed within 3-5-seriate, while multiseriate rays in Celtis a growth ring because in some samples crys are often heterocellular and typically 6-10- tals occur most frequently near growth ring seriate (e.g., Panshin & De Zeeuw 1980; boundaries. Tables 1 & 2, this paper). In addition to these features, we found that crystal location, and Celtis pallida colour and fluorescence of water extracts also Characteristics of Celtis pal/ida are illus can be useful in distinguishing between these trated in Figures 37-40. two genera. Growth rings distinct to indistinct, marked In Ulmus, crystals occur in the axial pa by thick-walled latewood fibres. Wood dif renchyma, while in Celtis, they occur in the fuse-porous. Vessels solitary and in radial ray parenchyma. Sweitzer (1971) examined multiples of 2-4 (up to 12, but rarely more 26 species (total of 41 samples) of Ulmus than 4), mean tangential diameters ranging and found crystals in both axial and ray from 58 to 79 J.lffi; mean tangential diameter parenchyma. However, we observed crystals of the 25 larger vessels ranging from 68 to 93 only in axial parenchyma of the six North )lm; 22 to 68 per sq. mm. Perforations ex American species (total of 68 samples). Short clusively simple; vessel elements short; range crystalliferous strands sometimes dissect the of sample mean vessel element lengths 179 rays (Fig. 14), and so in tangential sections (s.d. '= 35) to 226 (s.d. '= 33) )lm; alternate crystals appear to be located in enlarged ray intervascular pits, non -vestured, medium parenchyma cells. But radial sections reveal large (8-12 )lm). Spiral thickenings absent. that the crystalliferous cells in the elms are Some vessels in some specimens with thick axial parenchyma, not ray parenchyma. Since walled (sclerotic) tyloses; thin-walled tyloses crystals do not occur in every sample, this in some vessels. Vessel element walls 4-7 feature is of limited utility and can only be J.lffi thick. used when crystals are present. Fibres non septate and fibre pits rare and In Ulmus, water extracts range from col without obvious borders. Range of sample ourless to shades of yellow and/or brown mean fibre lengths of 696 (s.d. = 120) to 711 and fluoresce shades of blue or green. In Cel (s.d. '= 103) )lm; thick-walled. tis, water extracts are colourless and do not Axial parenchyma predominantly para fluoresce. Thus, shavings from an unknown tracheal, confluent-banded, bands 2-8 cells that test positive (i.e., fluoresce and/or pro wide; strands mainly of 2-4 cells. duce a coloured water extract) must be Ul Rays not storied; multi seriate rays hetero mus, and shavings that test negative (i.e., do cellular with uniseriate margins containing 1 not fluoresce or have a colourless extract) to 5 rows of square and upright cells, multi could be either Ulmus or Celtis. seriate rays 2 to 4 (rarely 5) cells wide. Uni seriate rays common, appearing to be com Vessel element lengths posed of only square and upright cells. Mean Vessel element lengths are remarkably number of rays per mm 9-11. Range of sam uniform within the elms and ring-porous ple mean height of the multiseriate rays 334 hack berries (Tables 1 & 2, Figs. 1 and 20), (s. d. = 160) to 411 (s.d. = 198) )lm. Soli and in the specimens in which earlywood and tary rhomboidal crystals common in ray pa latewood were macerated separately, little or renchyma cells, more common in the square no difference in vessel element length be and upright marginal cells of the multiseriate tween earlywood and late wood was found. rays and in the uniseriate rays than in the pro Moreover, the values we obtained for mean cumbent cells. vessel element length are similar to those reported by Panshin and De Zeeuw (1980; U. Discussion americana '= 220 )lm, s.d. '= 40, U. rubra '= Ulmus versus Celtis 220 ).tm, s.d. = 30; U. thomasii = 250 ).tm, Woods of Ulmus and Celtis are usually s.d. = 30; Celtis occidentalis = 260 )lm, s.d. distinguished by ray structure; all multiseriate = 30). Ecological and latitudinal variations in Downloaded from Brill.com10/06/2021 12:53:49PM via free access 20 IAWA Bulletin n.s., Vol. 10 (1),1989 Table 3. Ulmus F pr> F Celtis F pr> F MID 60.06 0.0001 MID 6.04 0.0063 :MRD 59.90 0.0001 :MRD 10.95 0.0003 MYEL 3.48 0.0076 MYEL 0.92 0.4093 %VE 26.03 0.0001 %VE 1.53 0.2405 MRH 1.59 0.1733 MRH 0.61 0.5483 TRH 2.85 0.2200 TRH 0.41 0.6660 RPMM 10.18 0.0001 RPMM 3.55 0.0414 Results of analysis of variance (ANOVA) for unbalanced design for selected quantitative features of species of Ulmus and Celtis. The F statistic and the probability of exceeding F (pr>F) is shown for each feature. The criteria for rejecting the null hypothesis that the species means were the same was pr>F less than 0.001. At least one of the species means is different for MTD, MRD, % VE, and RPMM for Ulmus, and for MRD for Celtis. MTD = mean tangential diameter of earlywood vessels. MRD = mean radial diameter of earlywood vessels. MVEL = mean vessel element length. %VE =per cent of tracheary elements that are vessel elements. MRH = mean ray height of multiseriate rays. TRH = IA WA 'standard list' ray height, average of the ten largest of the 25 larger rays. RPMM = Rays per mm. vessel element lengths have received con Ray height siderable attention in recent years and it is Ray height is a variable character, and de well documented that tropical floras are char termining the best method of measuring and acterised by longer vessel elements than xeric describing this feature is problematic. Both or temperate floras (e.g., Baas et al. 1983; mean ray height and mean height of the ten Carlquist 1975). Vessel element lengths are tallest rays are highly variable within a spe similar in all ring-porous species of Celtis cies (Tables 1 & 2). For the Ulmaceae, mea regardless of their habitat. Vessel element suring 'larger rays' may be a less repro lengths are not shorter in Celtis reticulata ducible method of describing ray height than which grows in more arid areas than the east mean ray height because different individuals ern species, C. occidentalis and C. laevigata. will have different perceptions of what is a This situation in Celtis parallels that observed 'larger' ray, and what is perceived as a larger within some other temperate latitude genera, ray will vary with the total area scanned in which vessel element lengths are similar in and the magnification used. Also, De Smidt species growing in Mediterranean, arid, and/ (1922) documented considerable within spe or mesic conditions (Baas et al. 1983). cies and within tree variation in multiseriate Relatively few samples were available of Cel ray height, width and volume in Ulmus rubra tis pallida, which is only a small tree or (syn. U.fulva Michx). Ray height should not shrub, and its vessel element lengths are be used to distinguish between species of a slightly shorter than the other species that genus in the Ulmaceae. However, ray height routinely achieve tree size. Vessel element is useful in distinguishing between Ulmus lengths of these U. S. species (species means and Celtis. There is a difference in both mean of 222-241 Jlm, Table 2) are shorter than ray height and mean height of the ten tallest those reported for species native to Cuba rays between Ulmus species (mean height: (282 ).l.m; Cox 1941) and the Philippines (317 251-304Jlm; tallest rays: 455-622Jlm) and Jlm and 400 ).l.m; Grumbles 1941). There ap Celtis species (mean height: 391-441 ).l.m; parently is latitudinal variation in vessel ele tallest rays: 728-897 ).l.m). ment length in Celtis. Downloaded from Brill.com10/06/2021 12:53:49PM via free access Wheeler, LaPasha & Miller- Wood anatomy of Ulmus and Celtis in the U.S.A. 21 Ulmus same is rejected for mean tangential diameter, mean radial diameter, percent vessel ele ,.. C:S.c-"' <'> ments, and number of rays per mm. Con E::I...c-~~ ~ ~ C'd 1,..j .... c:s 0 oV'l s-. ..., U en sequently, these characters can be useful am am in distinguishing between species of Ulmus. ru ru The null hypothesis cannot be rejected for th th mean vessel element length, mean ray width, a l al or mean ray height using the criteria adopted cr cr here which suggests that these characters are sc se not useful in distinguishing between species MTD MRD of Ulmus. Pairwise comparisons of the Ulmus spe cies are summarised in Figure 41. Only com parisons for the characters (mean tangential E::s..c-~O) E :s.c \-0 <.> «i 1-0 _ ~ u V".:- ~ 1-0 _ :\l 0 tn diameter, mean radial diameter, per cent ves am sel elements, and rays per mm) in which the ru ru initial null hypothesis was rejected are lh lh shown. For a given feature, pairs of species al al not significantly different at the 0.05 level cr cr cannot be distinguished using the sampling se se methods of this study. %VE RPMM Distinguishing between species of Ulmus Celtis Soft elms vs. hard elms - Soft elms have a lower specific gravity (green volume, '" g e ovendry weight, generally less than 0.5), and LJNot significant at 0.05% larger earlywood pores (mean tangential ocl a~ . level diameters of 145-240 )lm), than the hard rc 'l* iii Significant at 0.05% level elms (specific gravity based on green volume MRD and ovendry weight, generally more than 0.5; mean tangential diameters of earlywood pores Fig. 41. Pairwise comparisons of species of 65-162 )lm). Moreover, in the soft elms the Ulmus and Celtis for selected quantitative earlywood pores form a near continuous features. Comparisons use studentised maxi band (Figs. 2, 3) and the crystal containing mum modulus and Sidek's uncorrelated-t in axial parenchyma cells are not inflated (Fig. equality, and an alpha level of 0.05 to deter 16), while in the hard elms the larger early mine significance. Comparisons significant at wood pores generally are more widely spaced the 0.05 level are shown in black. MTD = (Figs. 4-7), and the crystal containing axial mean tangential diameter of earlywood ves parenchyma cells are inflated (Figs. 14, 15). sels. MRD = mean radial diameter of early Recent work on foliar flavonoids of Ulmus wood vessels. % VE = per cent of tracheary native to eastern North America found there elements that are vessel elements. RPMM = were two chemical groups, corresponding rays per mm. For species abbreviations, see to the wood anatomical groups (Sherman & Fig. 1 and Fig. 20. Giannasi 1988). Soft elms - Ulmus americana generally has a single continuous row (Fig. 2) of large diameter earlywood pores; however, when Statistics for Ulmus growth rings are wide, 10 mm or more, there Results of statistical analyses of quantita may be more than one row of larger vessels tive features of elm are presented in Table 3. in those wide rings. Ulmus rubra consistently Based on the results of the ANOY As, the null has 2-4 rows of large diameter earlywood hypothesis that the species means are the vessels (Fig. 3). Downloaded from Brill.com10/06/2021 12:53:49PM via free access 22 IAWA Bulletin n.s., Vol. 10 (1),1989 Hard elms - Although there is consid gential bands are well-developed in such erable overlap in the characters studied (see samples and occur throughout the growth Table 1), it is possible by use of a combina ring. These samples also have high percent tion of characters (colour of water extract, ages of vascular tracheids, Ulmus crassifolia earlywood vessel diameters and spacing, and has the highest percentages of vascular tra parenchyma abundance) to distinguish be cheids of the four species (Table 1). tween some, but not all, specimens of the four hard elm species. The similarity in wood Comments on ring-porosity in the hard elm: anatomy of the hard elms lends support to Ring-porosity is considered a derived char the suggestion, based on flavonoid data, that acter (Gilbert 1940) and the fossil record sup these four species are closely related (Sher ports this view (Page 1981; Scott & Wheeler man & Giannasi 1988). 1982). Previous studies of the Ulmaceae Ulmus thomasii (Figs. 1,5; Table 1) gen (Sweitzer 1971; Cox 1941) indicate that in erally has larger earlywood pores than the the Ulmaceae ring-porous wood is advanced. other hard elms. It has the least amount of Sweitzer (1971) found that radial multiples parenchyma; there is less parenchyma asso are frequent in the diffuse-porous and semi ciated with the vessels and only rarely an ring-porous Ulmaceae woods, while tangen occasional isolated cell of diffuse paren tial bands of pore clusters are frequent in the chyma, and marginal parenchyma is present, ring-porous species. Vascular tracheids occur but often not well-defined (Fig. 8). Crystals only in the ring-porous species (Sweitzer are rare in U. thomasii and only one strand of 1971). Some samples of Ulmus crassifolia crystalliferous parenchyma was seen in one do not appear ring-porous, but Ulmus crass i of eighteen specimens examined. It is the folia has the highest percentage of vascular only species with a yellow-coloured water tracheids of any Ulmus species (Table 1), extract (Table 1). and in those woods without an 'earlywood Ulmus serotina (Fig. 4) has the most pore ring' there is a pronounced pattern of closely spaced earlywood vessels, and the wavy tangential to diagonal vessels. Because most oval-shaped vessels. It differs from the U. crassifolia has these two features, which other species of Ulmus in that it flowers in are associated with ring-porous woods, this the fall, its common name September elm suggests it may show a 'secondary loss' of refers to this characteristic. False growth ring-porosity. The trend leading to a loss of rings were observed in two of the four U. a distinct earlywood pore ring includes a de serotina samples available. False rings may crease in earlywood vessel diameter accom be more common in this species because of panied by an increase in the distance between the fall flowering and the associated changes the larger earlywood pores. The phylogenetic in auxin levels that would be associated with trend from scalariform perforation plates to flowering. simple perforations is, to date, the only ma Ulmus alata (Fig. 6) has somewhat nar jor trend in vessel element evolution that is rower and more widely spaced early wood not known to be reversible to some degree vessels than U. thomasii. Ulmus alata has (Dickison, in press; Baas 1986; Carlquist more parenchyma (Fig. 9) than U. thomasii; 1980). marginal parenchyma is more obvious, more parenchyma is associated with the vessels, Comparison with fossil elms from the United and in the last formed latewood, diffuse and States diffuse-in-aggregate apotracheal parenchyma Woods with anatomy similar to extant' is more frequent. species of elm have been been present in Ulmus crassifolia (Fig. 7) has the narrow North America since at least the Miocene. est and most widely spaced earlywood ves Three species of fossil woods assigned to sels of the four species of hard elm. Some Ulmus have been described from the Miocene specimens (e.g., BWCw 8680, BWCw Vantage Fossil Forests of Oregon (Prakash 8559), do not look ring-porous as the early & Barghoorn 1961a; 1961b). One species, wood lacks large solitary pores. Wavy tan- U. baileyana, was said to resemble U. rubra; Downloaded from Brill.com10/06/2021 12:53:49PM via free access Wheeler, LaPasha & Miller- Wood anatomy of Ulmus and Celtis in the U.S.A. 23 U. miocenica was said to resemble U. ameri Distinguishing between species of Celtis cana; and U. pacifica did not compare closely Cox (1941) found no distinction between with any extant species of Ulmus. The total the wood structure of C. occidentalis and C. range of vessel element lengths (130-460 laevigata (syn. C. mississippiensis). As men 11m) in U. bai/eyana is greater than in the tioned above, we also found no significant extant U. rubra (total range of 100-335 11m). differences between these two species in the The occurrence of vessel elements longer in features we examined (see Tables 2 & 3), al fossil woods than in recent woods that the though crystals are more common in C. laevi fossils resemble is not surprising and is con gata than in C. occidentalis. One sample of sistent with the well established evolutionary C. laevigata (BWCw 8303) collected in Flori trend from long to short vessel elements. da appears more semi-ring-porous than ring Such differences in vessel element lengths porous. This sample had exceptionally wide have been reported previously (Manchester growth rings (more than 10-12 mm). Pore 1979). Vessel element lengths in U. mio size decreased gradually throughout the cenica (153-367 11m) are closer to the extant growth ring and tangential bands were not species of elm. Abundant tyloses in U. paci pronounced until the latter part of the late fica obscured vessel element end walls and it wood. Sweitzer (1971) earlier found that was not possible to determine vessel element wood of Planera aquatica (another member of lengths in this species. Although U. mioceni the Ulmaceae) varied from diffuse-porous to ca was compared to U. americana, accom ring-porous. panying descriptions and illustrations indicate Only a few samples of C. tenuifolia (Fig. its characteristics are more similar to the hard 22) and C. lindheimeri (Fig. 23) were avail elms, not the soft elms. The early wood pores able for study, and so they were not included of U. miocenica are not in a continuous row, in the statistical analyses. On the basis of the and their mean tangential diameter is 118 11m, limited material examined, however, it ap a value too small for American elm and slip pears that these species have anatomy indis pery elm, but characteristic of the hard elms. tinguishable from the other species of Celtis. Also, illustrations show that the crystal con Earlywood pores in C. reticulata (Figs. taining axial parenchyma strands of U. mio 24-26) tend to be more rounded in outline cenica are inflated, a characteristic of the hard than in the other species. Mean radial diam elms, but not of American elm or slippery eter was less than mean tangential diameter in elm. 5 of the 12 C. reticulata samples examined, in all other species mean radial diameter was Statistics for Celtis greater than mean tangential diameter. The Results of statistical analyses of quantita differences in mean radial diameter of early tive features of hackberry are presented in wood pores between C. reticulata and C. oc Table 3. Based on the results of the ANOVAs, cidentalis or C. laevigata are statistically sig the null hypothesis that the species means are nificant (Table 3; Fig. 41). However, this the same is rejected for mean radial vessel difference may be an environmental differ diameter. This character may be useful in dis ence. Celtis reticulata grows in the most arid tinguishing between these species of Celtis. habitats of all the ring-porous species stud The null hypotheses cannot be rejected for the ied, and its growth rings are the narrowest. remaining characters tested, using the criteria Radial diameters, and vessel shape are cor adopted here. This suggests that these char related with growth ring width in Celtis; if acters may not be useful in distinguishing rings are wide, the transition from earlywood between these species of Celtis. to latewood is more gradual, and pores are Pairwise comparisons of the Celtis species more oval in outline than they are if the rings using mean radial vessel diameter are shown are narrow (Figs. 24-26). Gasson (1987) in Figure 41. Using the sampling methods found vessel shape (eccentricity) in Quercus of this study, C. laevigata and C. occidentalis robur L. to be strongly influenced by radial cannot be distinguished by mean radial vessel growth rate, i.e. the wider the rings the more diameter. oval in outline the pores are. Downloaded from Brill.com10/06/2021 12:53:49PM via free access 24 IAWA Bulletin n.s., Vol. 10 1989 Celtis pallida (Figs. 37-40) is distinct Chattaway, M.M. 1932. Proposed standards from the other species of Celtis described for numerical values in describing woods. herein because it is diffuse-porous, rather Trop. Woods 29: 20-28. than ring-porous, vessels are frequently in Constantine, A., Jr. 1975. Know your radial multiples and not in a diagonal to woods. Charles Scribner's & Sons, New tangential pattern, and it has narrower rays. York. Celtis pallida is evergreen (Elias 1980). Cox Core, H.A., W.A. Cote & A.C. Day. 1979. (1941), Grumbles (1941) and Sweitzer (1971) Wood. Structure and identification. 2nd found that evergreen species of Celtis are Ed. Syracuse University Press, Syracuse. diffuse-porous and deciduous species are Cox, M.J. 1941. The comparative anatomy ring-porous. The characteristics of C. pallida of the secondary xylem of five American are similar to those of other diffuse-porous species of Celtis. Amer. Midland Nat. 25: species of Celtis previously described Al 348-357. though vessel elements in C. pallida are Dickison, W. C. In press. Steps toward the slightly shorter than in the ring-porous spe natural system of the dicotyledons: stem cies (sample means of 179 to 226 J.l.m com anatomy. Aliso. pared to 176 to 286 J.l.m), fibres in C. pallida Elias, T.S. 1970. The genera of Ulmaceae in are considerably shorter (sample means of the southeastern United States. J. Arnold 696 to 711 J.l.m compared to 1090 to 1167 Arbor. 51: 18-40. 11m) and there are different fibre length/ves - 1980. Trees of North America. Book sel element length ratios (F/V). Celtis pallida Division, Time Mirror Mag., New York. generally is a shrub while the other species Furuno, T. 1985. Anatomy of North Ameri are trees; shrubs generally have shorter fusi can woods. An Atlas of light and scanning form elements than trees. Vessel element electron micrographs. 1. Hardwoods. lengths reflect fusiform initial length. Conse Studies of the San'in Region, Research quently, the difference in fibre lengths be Data and Source Material No. 1. tween C. pallida and the other species of Cel Gasson, P. 1987. Some implications of ana tis and the different F/V ratios cannot be at tomical variations in the wood of pedun tributed to fusiform initial length, but to dif culate oak (Quercus robur L.), including ferences in elongation during differentiation. comparison with common beech (Fagus sylvatica L.). IAWA Bull. n. s. 8: 149- Acknowledgements 166. This work was supported in part by a Gilbert, S. G. 1940. Evolutionary signifi grant from the National Science Foundation cance of ring porosity in woody angio (BSR 8708010). sperms. Bot. Gaz. 102: 105-120. Grumbles, T.L. 1941. The comparative anat References omy of the secondary xylem of four Baas, P. 1986. Ecological patterns in xylem oriental species of Celtis. Lloydia 4: 145- anatomy. In: On the economy of plant 152. form and function (ed. T.J. Givnish): Hoadley, R.B. 1980. Understanding wood. 327-352. Cambridge Univ. Press, Cam Taunton Press, Newtown, Conn. bridge. Hochberg, Y. 1974. Some conservative gen - , E. Werker & A. Fahn. 1983. Some eco eralizations of the T-method in simul logical trends in vessel characters. IAWA taneous inference. J. Multivariate Analysis Bull. n.s. 4: 141-159. 4: 224-254. Carlquist, S. 1975. Ecological strategies of Jane, F. W. 1970. The structure of wood. xylem evolution. Univ. California Press, 2nd Ed. A. & c. Black Ltd., London. Berkeley. Manchester, S.R. 1979. Triplochitioxylon - 1980. Further concepts in ecological wood (Sterculiaceae): a new genus of wood anatomy, with comments on recent work from the Eocene of Oregon and its bearing in wood anatomy and evolution. Aliso 9: on xylem evolution in the extant genus 499-553. Triplochiton. Amer. J. Bot. 66: 699-708. Downloaded from Brill.com10/06/2021 12:53:49PM via free access Wheeler, LaPasha & Miller - Wood anatomy of Ulmus and Celtis in the U.S.A. 25 Metcalfe, C.R. & L. Chalk. 1950. Anatomy Sherman, S.L. & D.E. Giannasi. 1988. Fo of the dicotyledons. Vol. 2. Clarendon liar flavonoids of Ulmus in eastern North Press, Oxford. America. Biochemical Systematics and Miller, R.B. 1981. Explanation of the cod Ecology 16: 51-56. ing. IAWA Bull. n.s. 2: 111-145. Sidak, Z. 1967. Rectangular confidence re Page, V.M. 1981. Dicotyledonous wood gions for the means of multivariate normal from the Upper Cretaceous of central distributions. J. Amer. Statistical Assoc. California. III. Conclusions. J. Arnold 62: 623-633. Arbor. 62: 437-455. Smidt, W.J. de. 1922. Studies of the distri Panshin, A.J. & C. de Zeeuw. 1980. Text bution and volume of the rays in slippery book of Wood Technology. 4th Ed. elm (Ulmus fulva Michx.). J. For. 20: McGraw-Hill Book Co., New York. 352-362. Prakash, U. & E.S. Barghoorn. 1961a. Sweitzer, E.M. 1971. Comparative anatomy Miocene fossil woods from the Columbia of the Ulmaceae. J. Arnold Arbor. 52: Basalts of central Washington. 1. Arnold 523-585. Arbor. 42: 165-203. Taylor, F.W. 1976. Fiber length variation - & - 1961b. Miocene fossil woods from within growth rings of certain angio the Columbia Basalts of central Wash sperms. Wood and Fiber 8: 116-119. ington, II. J. Arnold Arbor. 42: 347- Wheeler, E.A. 1986. Vessels per square 362. millimetre or vessel groups per square Scott, R.A. & E.F. Wheeler. 1982. Fossil millimetre? IAWA Bull. n.s. 7: 73-74. woods from the Eocene Clarno Formation Wilson, K. & D.1.B.White. 1986. The anat of Oregon. lAW A Bull. n. s. 3: 135- omy of wood: its diversity and variability. 154. Stobart & Son Ltd, London. APPENDIX 1 Wood anatomical key to the native North American species of Celtis and Ulmus Latewood vessels not in wavy tangential or diagonal bands, wood diffuse porous spiny hackberry (Celtis pallida) Latewood vessels in wavy tangential or diagonal bands ...... see below Largest rays commonly lO-12-seriate, some rays always wider than 7-seriate; rays essen tially heterocellular; crystals present in ray cells, absent in axial parenchyma cells; heartwood cream to yellowish gray...... CELTIS Wood distinctly ring porous ...... sugarberry (C. laevigata) Lindheimer hackberry (c. lindheimeri) hackberry (C.occidentalis) netleafhackberry (c. reticulata) Georgia hackberry (c. tenuifolia) Largest rays generally 4-5-seriate, rarely 6-seriate and never over 7-seriate; rays essentially homocellular; crystals absent in ray cells, present or absent in axial parenchyma cells; heart- wood light brown to brown or reddish brown ...... ULM U S Downloaded from Brill.com10/06/2021 12:53:49PM via free access 26 IAWA Bulletin n.s., Vol. 10 1989 Earlywood pores generally visible to the naked eye, mostly in a continuous row; range of means (tangential diameter), 145-240 11m or maximum diameter generally over 200 11m; specific gravity (based on green volume) generally less than 0.50 ...... SOFf ELMS Earlywood pores mostly in single rows; heartwood not fluorescent; heartwood tan to light brown ...... American elm (U. americana) Earlywood pores in multiseriate rows; heartwood fluorescent yellow-green; heart- wood brown to reddish brown ...... slippery elm (U. rubra) Earlywood pores generally not visible to the naked eye, mostly in a discontinuous row; range of means (tangential diameter), 65-162 11m or maximum diameter generally less than 200 11m; specific gravity (based on green volume) generally more than 0.50 HARD ELMS Water extract of heartwood yellow. Earlywood pores range of means (tangential diameter), 125-162 11m, mean distance between pores 80-270 11m; wood ring- porous; crystals absent or very rarely present ...... rock elm (U. thomasii) Water extract of heartwood brown, yellow-brown or red-brown. Earlywood pores range of means (tangential diameter), 65-143 11m, mean distance between pores 90- 850; wood ring-, semi-ring- or diffuse-porous; crystals generally present in axial parenchyma cells in short chains. Earlywood pores generally greater than 100 11m in tangential diameter, distance between pores generally less than 90-380 11m; consistently ring-porous Earlywood pores more oval in outline, mean radial diameter 160 11m, mean distance between solitary earlywood pores 90-190 September elm (U. serotina) Earlywood pores less oval than above, mean radial diameter 130 11m, mean distance between earlywood pores 155-380 11m ... winged elm (U. alata) Earlywood pores generally less than 100 11m in tangential diameter, mean dis tance between solitary earlywood pores 160-805 11m; wood often not ring- porous ...... cedar elm (U. crassifolia) Downloaded from Brill.com10/06/2021 12:53:49PM via free access