Ostrya (Betulaceae) in the Southwestern United States Based on Leaf Morphology

A taxonomic reevaluation of the genus Ostrya (Betulaceae) in the Southwestern United States based on leaf morphology

Stephanie Dykema and Ross A. McCauley Fort Lewis College, Department of Biology, Durango, CO

BACKGROUND AND INTRODUCTION RESULTS DISCUSSION Ostrya is a genus of small deciduous trees in the birch family, Betulaceae, commonly Morphometric analyses of Ostrya in the SW US provides evidence that one variable A B known as hop-hornbeam. The genus represents an ancient Holarctic plant distribution 160 80 40 species likely exists in this region (Figure 3-6). Though several taxa have been a a a a A. Leaf Length 70 B. Leaf Width 35 C. Width +30° and occurs in deciduous forests of Asia and Europe as well as in eastern North A B 140 a proposed for the SW US our data indicates that insignificant morphological variation America in abundance with isolated populations found in the dryer mountains of the 120 60 30 exists among populations across the region to support the segregation of species. 100 50 c 25 c b a b b b b southwestern United States and NW Mexico, extending south as a cloud forest 80 c 40 b 20 The distinction of O. baileyi in the Guadalupe Mountains and O. chisosensis in the b b b c b b b b b b

Leaf Length (mm)

Width of Leaf (mm) Leaf of Width b b b 15 60 30 c c b b (mm) +30° at Leaf of Width endemic through central Mexico to Honduras (Furlow, 1990). The number of species b c c Chisos Mountains was based principally off of differences in the expression of stipitate 40 c 20 c 10 c c c c c c c within North American Ostrya is small (3-5) and has been debated by systematists. c c glands on the twigs and petioles with O. baileyi showing prominent glands and O. 20 10 5 Ostrya populations in the eastern U.S. have been commonly recognized as Ostrya chisosensis lacking these glands (Rose, 1905; Correl 1965). Additional variations in O. chisosensis O. chisosensis O. chisosensis O. virginiana - OH O. knowltonii - UT O. virginianaO. - WVvirginiana - OH O. knowltonii - UT O. virginianaO. - virginianaWV - OH O. knowltonii - UT O. virginiana - WV

O. knolwtonii - Alamo Cyn virginiana (Mill.) K. Koch (Brain and Spamer, 2000) however, the grouping of O. knolwtonii - Alamo Cyn O. knolwtonii - Alamo Cyn O. baleyi - GUMO Dog Cyn O. baleyi - GUMO Dog Cyn leaf shape, leaf margin characteristics, and pubescence were also suggested (Furlow O. baleyi - GUMO Dog Cyn O. knowltonii - Oak Creek Cyn O. knowltonii - Oak Creek Cyn O. knowltonii - Oak Creek Cyn O. knowltonii - GRCA Bright Angel O. knowltonii - GRCA Bright Angel O. knowltonii - GRCA Bright Angel O. baleyi - GUMO Pine Springs Cyn O. baleyi - GUMO Pine Springs Cyn O. baleyi - GUMO Pine Springs Cyn O. knowltonii - GRCA Roaring Springs O. knowltonii - GRCA Roaring Springs populations in the southwest has not been so easily agreed upon. D O. knowltonii - GRCA Roaring Springs 1990) however, these characteristics were merely observed in few collected 60 40 50 specimens. Our field observations and morphological analysis indicated that these

D. Width +60° 35 E. Width -30° a F. Width -60° 50 a a The isolated and disjunct occurrences of Ostrya across the SW US have led to the a 40 characters are in fact variable within populations and thus do not serve as a means for 30 40 b recognition of one to three distinct species (Figure 1 & 2). Some botanists group the 30 b b segregating taxon groups. C 25 b b 30 b b b b a a b b 20 b b southwestern populations under the single species Ostrya knowltonii Coville. The b b 20 b b b b b b c 20 b b b c

Width of Leaf at -30° at Leaf of Width Width of Leaf at +60° 15 genus has been further segregated, however, by some researchers based primarily on Width of Leaf at -60° (mm) 10 Phenotypic plasticity is likely responsible for much of the morphological variation 10 geographic location and variation in fine-scale leaf morphology. Populations of the 10 observed across the sampled populations. One particular example was the consistent 0 5 0 Guadalupe Mountains have been referred to as O. baileyi Rose and populations divergence of the Oak Creek Canyon, AZ population from the remaining O. knowltonii O. chisosensis O. chisosensis O. chisosensis O. virginianaO. - virginianaWV - OH O. knowltonii - UT O. virginianaO. - WVvirginiana - OH O. knowltonii - UT O. virginianaO. - virginianaWV - OH O. knowltonii - UT

O. knolwtonii - Alamo Cyn O. knolwtonii - Alamo Cyn O. knolwtonii - Alamo Cyn restricted to the Chisos Mountains in Texas and the Sierra del Carmen in Coahuila as O. baleyi - GUMO Dog Cyn O. baleyi - GUMO Dog Cyn O. baleyi - GUMO Dog Cyn populations. The ecosystem where this population grows is more moist and highly O. knowltonii - Oak Creek Cyn O. knowltonii - Oak Creek Cyn O. knowltonii - Oak Creek Cyn O. knowltonii - GRCA Bright Angel O. knowltonii - GRCA Bright Angel O. knowltonii - GRCA Bright Angel O. baleyi - GUMO Pine Springs Cyn O. baleyi - GUMO Pine Springs Cyn O. baleyi - GUMO Pine Springs Cyn O. chisosensis. Under this segregated view O. knowltonii is restricted to the Colorado A.O. knowltonii - GRCA Roaring Springs O. knowltonii - GRCA Roaring Springs O. knowltonii - GRCA Roaring Springs vegetated than the open environments more commonly inhabited by Ostrya in the SW River drainage in northern Arizona and southern Utah. No systematic study has been 14 a 22 16 (Figure 7). The larger trees and larger leaves are likely a physiological response to G. Petiole Length a 20 a H. Number of Veins b I. Number of Teeth 12 a a 14 conducted to consider the distinction of each population in relation to each other and 18 lower light levels in this ecosystem which approaches the understory habitat of O. 10 12 16 a a evaluate the validity of the proposed taxonomic delineation (Furlow, 1990). 8 a a c c 10 a virginiana and represents an inherent adaptability within the genome of the species. 14 b a a a 6 a 8 12 a a b b a

Figure 2. Species of Ostrya illustrating habit, leaf morphology, and (mm) Length Petiole 4 b c b b b 6 The purpose of this study was to c 10 b b reproductive structures. A. Collecting O. knowltonii near Moab, UT B. c c This study supports the view that the SW US populations of Ostrya represent a single 2 c b 8 c 4 b c c Number of Veins on One Side of Leaf examine the distribution and b b Infructescence O. knowltonii, Alamo Canyon, NM C. O. baileyi with 0 6 2 taxon which should be referred to as Ostrya knowltonii Coville. Additional molecular morphological variation of Ostrya in the staminate catkin at type locality in Dog Canyon, Guadalupe Mountains Veins Primary 4th and 3rd the Between Teeth of Number O. chisosensis O. chisosensis O. chisosensis phylogenetic data for these populations inferred from four independent gene regions O. virginiana - OH O. virginiana - OH National Park, TX D. O. knowltonii in Roaring Springs Canyon, Grand O. virginiana - WV O. knowltonii - UT O. virginianaO. - virginianaWV - OH O. knowltonii - UT O. virginiana - WV O. knowltonii - UT O. knolwtonii - Alamo Cyn O. knolwtonii - Alamo Cyn O. knolwtonii - Alamo Cyn southwestern United States to gain a O. baleyi - GUMO Dog Cyn O. baleyi - GUMO Dog Cyn O. baleyi - GUMO Dog Cyn O. knowltonii - Oak Creek Cyn O. knowltonii - Oak Creek Cyn O. knowltonii - Oak Creek Cyn additionally showed only minor nonspecific variation across the region (Bielz and O. knowltonii - GRCA Bright Angel O. knowltonii - GRCA Bright Angel O. knowltonii - GRCA Bright Angel O. baleyi - GUMO Pine Springs Cyn O. baleyi - GUMO Pine Springs Cyn O. baleyi - GUMO Pine Springs Cyn Canyon National Park, AZ. O. knowltonii - GRCA Roaring Springs O. knowltonii - GRCA Roaring Springs clear understanding of the taxonomic O. knowltonii - GRCA Roaring Springs McCauley, 2013). Likely these isolated and disjunct occurrences represent relictual 5 6 280 delineation of the species. This work c J. Length of Smallest K. Length of Largest 260 a L. Length to Width a habitat islands representing the remnants of a wider continuous distribution contracted 4 5 Tooth 240 Ratio represents a contribution to an ongoing Tooth a a a a 220 a by long-term climatic changes. 3 a 4 a systematic revision of the genus across a b a a 200 a b c d d c a 180 2 3 d a a North America and consisted of a a b 160 b d c B a a b Future investigations of morphological variation in North American Ostrya are needed b 140 d c d 1 (mm) Tooth Largest of Length 2 A (mm) Tooth Smallest of Length b b d morphometric analyses of leaf form b b Width Leaf to Length Leaf of Ratio b b 120 to test the hypothesis that isolated occurrences of Ostrya in the Madrean Sky Islands b b b b b across ten populations of Ostrya. 0 1 100 and Copper Canyon region of NW Mexico represent a southern extension of O.

O. chisosensis O. chisosensis O. chisosensis O. virginiana - OH O. virginiana - WV O. knowltonii - UT O. virginianaO. - WVvirginiana - OH O. knowltonii - UT O. virginianaO. - WVvirginiana - OH O. knowltonii - UT knowltonii. Additionally the circumscription and affinities of the cloud forest O. knolwtonii - Alamo Cyn O. knolwtonii - Alamo Cyn O. knolwtonii - Alamo Cyn O. baleyi - GUMO Dog Cyn O. baleyi - GUMO Dog Cyn O. baleyi - GUMO Dog Cyn O. knowltonii - Oak Creek Cyn O. knowltonii - Oak Creek Cyn O. knowltonii - Oak Creek Cyn O. knowltonii - GRCA Bright Angel O. knowltonii - GRCA Bright Angel O. knowltonii - GRCA Bright Angel O. baleyi - GUMO Pine Springs Cyn O. baleyi - GUMO Pine Springs Cyn O. baleyi - GUMO Pine Springs Cyn O. knowltonii - GRCA Roaring Springs O. knowltonii - GRCA Roaring Springs O. knowltonii - GRCA Roaring Springs occurrences across the Sierra Madre Occidental, Sierra Madre Oriental, and Southern

42 A. 45 50 Cordillera of Mexico currently viewed as conspecific with O. virginiana need to be 40 M. Ratio of Leaf c N. Ratio of Leaf O. Ratio of Leaf c b a 38 c Width +60° c Width +30° c 40 Width -30° b b 45 c c evaluated. 36 c c Figure 1. Distribution of Ostrya in a a 34 a a Figure 3. Multivariate analysis of ratio data. PCA. Centered data. a a 35 a 40 the SW United States and NW Mexico 32 a a a a Log10 transformed. No pattern is apparent with the SW populations but 30 a a a 30 c 35 c based on herbarium records. 28 c the O. virginiana of WV and OH show distinct segregation. b c b c b 26 c b a b 24 b 25 b 30 c c 22

Ratio of Leaf Width at -30° and Leaf Length Leaf and -30° at Width Leaf of Ratio a c Length Leaf and +60° at Width Leaf of Ratio METHODS C Length Leaf and +30° at Width Leaf of Ratio b 20 20 25 Figure 7. Ostrya habitat in Oak • Ten populations representing all known areas of occurrence and each putative O. chisosensis O. chisosensis O. chisosensis O. virginianaO. - WVvirginiana - OH O. knowltonii - UT O. virginianaO. - WVvirginiana - OH O. knowltonii - UT O. virginianaO. - WVvirginiana - OH O. knowltonii - UT

O. knolwtonii - Alamo Cyn O. knolwtonii - Alamo Cyn O. knolwtonii - Alamo Cyn Creek Canyon, AZ O. baleyi - GUMO Dog Cyn O. baleyi - GUMO Dog Cyn O. baleyi - GUMO Dog Cyn taxon were sampled in the field during the summers of 2012 and 2013. Ten O. knowltonii - Oak Creek Cyn O. knowltonii - Oak Creek Cyn O. knowltonii - Oak Creek Cyn O. knowltonii - GRCA Bright Angel O. knowltonii - GRCA Bright Angel O. knowltonii - GRCA Bright Angel O. baleyi - GUMO Pine Springs Cyn O. baleyi - GUMO Pine Springs Cyn O. baleyi - GUMO Pine Springs Cyn branches, each from a separate tree, were collected from each population and were O. knowltonii - GRCA Roaring Springs O. knowltonii - GRCA Roaring Springs O. knowltonii - GRCA Roaring Springs D 60 30 55 P. Ratio of Leaf c Q. Number of Teeth b pressed and dried for preservervation in the Fort Lewis College Herbarium (FLD). 25 Width -60° Ratio 50 c b • Morphological measurements were recorded for the largest leaf of each sample. c c c 20 a a 45 a a a a 40 15 a a The following morphological characteristics were measured: petiole length (mm), a a a 35 a a 10 b leaf lamina length (mm), leaf lamina width at widest point (mm), lamina width +30° c c b b b 30 b 5 b LITERATURE CITED 25 b b

(mm), lamina width +60° (mm), lamina width -30° (mm), lamina width -60° (mm), Length Leaf and -60° at Width Leaf of Ratio

Ratio of Number of Teeth Between 3rd and 4th and 3rd Between Teeth of Number of Ratio Length Leaf and Veins Primary 20 0 number of primary leaf veins (one side of leaf), stipitate glands on petiole (no=0, BIELZ, A. and R. A. MCCAULEY. 2013. Using DNA barcoding to evaluate species circumscription in O. chisosensis O. chisosensis yes=1), stipitate glands on leaf lamina (no=0, yes=1), abaxial pubescence desity E O. virginianaO. - WVvirginiana - OH O. knowltonii - UT O. virginianaO. - WVvirginiana - OH O. knowltonii - UT O. knolwtonii - Alamo Cyn O. knolwtonii - Alamo Cyn the genus Ostrya (Betulaceae) in the southwestern US. Fort Lewis College Department of Biology Figure 4. Multivariate analysis of continuous data. PCA. Centered data. O. baleyi - GUMO Dog Cyn O. baleyi - GUMO Dog Cyn O. knowltonii - Oak Creek Cyn O. knowltonii - Oak Creek Cyn O. knowltonii - GRCA Bright Angel O. knowltonii - GRCA Bright Angel O. baleyi - GUMO Pine Springs Cyn O. baleyi - GUMO Pine Springs Cyn (lite=0, moderate=1, dense=2), adaxial pubescence density (lite=0, moderate=1, Log10 transformed. O. virginiana of the Eastern states shows clear O. knowltonii - GRCA Roaring Springs O. knowltonii - GRCA Roaring Springs Senior Research Poster. dense=2), number of margin teeth (between the 3rd and 4th secondary veins on segregation. O. knowltonii of Oak Creek Canyon, AZ trends toward variation one side of leaf), depth of largest measured tooth (mm), depth of smallest of O. virginiana segregating from the remaining SW populations. Figure 6. Results of univariate morphometric analyses using 11 measured variables and 6 composite ratio BRIAN, N.J. AND E.E. SPAMER. 2000. Knowlton Hop-Hornbeam Revisited (Ostrya variables on leaf morphology in 10 populations of Ostrya. Shaded areas indicate the mean and 25th and knowltonii Cov.). Bartonia 60: 49-56. measured tooth (mm). To eliminate gross size differences ratios were calculated F 75th percentiles of the data with whiskers representing the 10th and 90th percentiles. Letters associated with between total lamina length and width and lamina length and width at +30°, +60°, - boxes indicate groupings of similar values determined through a Tukey Post Hoc Test (P<0.001). Several CORREL, D.S. 1965. Some additions and corrections to the flora of Texas. Wrightia 3: 126-129. 30°, and -60°. characteristics show variation only between the Eastern populations and the Southwestern populations • Univariate analyses were conducted by constructing box plots representing however the WV and OH populations are significantly similar to most of the SW populations for the majority FURLOW, J. J. 1990. The genera of Betulaceae in the southeastern United States. Journal of the variation within individual populations using SigmaPlot Ver. 12. Differences among of the measured characteristics. Variation between the Eastern O. virginiana and the Grand Canyon Arnold Arboretum 71: 1-67. populations as well as the Utah population can be seen for many of the characteristics. The Oak Creek the means of populations were determined using a One-way Analysis of Variance Canyon, AZ population is significantly different from the rest of the SW populations but similar to the ROSE, J. N. 1905. Notes on Ostrya, with two new species. Contributions from the United States followed by a Tukey Post hoc test to determine significant differences using SPSS Eastern populations for petiole length and length of largest tooth and is significantly different from all other National Herbarium 8: 291-293. Ver. 18. populations for length of smallest tooth. • Three multivariate analyses were conducted using MVSP (MultiVariate Statistical Package) Ver. 3.22: 1) Principal Components Analysis (PCA) of all continuous data. ACKNOWLEDGEMENTS Data was centered and log10 transformed. 2) PCA of ratio data. Data was centered and log10 transformed and 3) Principal Coordinates Analysis (PCoA) including all Figure 5. Multivariate analysis of continuous and discrete data. PCoA. O. Funding for this project was provided by the Fort Lewis College Faculty continuous and discrete data (minus ratios) using the Gower General Similarity virginiana of OH and WV is distinctly segregated. The Oak Creek Canyon, AZ Development Grant program. Research permits were granted by Grand Canyon Coefficient. population shows variation but is still united with the rest of the SW populations. N.P., Guadalupe Mountains N.P., and Big Bend N.P. to R. McCauley.