Functional leaf and stem traits of the Oaks of the Americas 
by Matthew A. Kaproth1,2^; Marlene Hahn3; Paul S. Manos4; Andrew L. Hipp3,5; Antonio González-Rodríguez6; and Jeannine Cavender-Bares1# 

1) Department of Ecology, Evolution, and Behavior, University of Minnesota, St. Paul, MN 55108, USA
2) Department of Biological Sciences, Minnesota State University Mankato, Mankato, MN 56001, USA
3) The Morton Arboretum, Lisle, IL 60532-1293, USA
4) Duke University, Durham, NC 27708, USA
5) The Field Museum, Chicago, IL 60605, USA
6) Instituto de Investigaciones en Ecosistemas y Sustentabilidad, Universidad Nacional Aut
onoma de Mexico, Antigua Carretera a Patzcuaro No. 8701, Col. Ex Hacienda de San Jose de la Huerta, Morelia, Michoacan 58190, Mexico

^matthew.kaproth@mnsu.edu; #cavender@umn.edu (corresponding author)

To capture interspecific variation, this data set includes 15+ functional traits for 135* American oak species. Two data files present (Oak.trait.means.csv and Functional leaf and stem traits of the Oaks of the Americas.csv): 
1) Petiole diameter (mm),
2) Petiole length (mm),
3) Leaf length (L; cm), 
4) Leaf Feret diameter (cm),
5) Leaf mass (g), 
6) Leaf area (A; cm2),
7) Specific leaf area (SLA; mm2 mg-1),
8) Total length of major veins per area (L/A; cm-1), 
9) Leaf perimeter length (P; cm)
10) Perimeter per unit leaf area (PLA; cm-1),  
11) Leaf lobedness (P/A)*L
12) Pubescence above (0-3),
13) Pubescence below (0-3), 
14) Stem specific density (SSD; g cm-3),
15) Stem mass (g), 
16) Stem diameter (mm),
17) Stem length (cm),
18) Stem volume (cm-3), 
19) Huber Value (stem area/leaf area) (HV; mm2 cm-2), 
20) Huber Value (stem area/leaf mass) (HV; mm2 g-1),
21) Total leaf area (cm2),
22) Total leaf mass (g).

Unless otherwise noted below, all traits were measured using functional trait methods outlined in Cornelissen et al. 2003 Handbook for functional traits or Tyree & Ewers 1991. Field-collected leaf and stem samples from sunlit branches were pressed and dried. Three fully expanded leaves from each individual of each species were scanned and analyzed for leaf surface area, perimeter length and perimeter per area using ImageJ software; they were then dried and weighed for SLA. Leaf pubescence was ordinal-ranked from 0 to 3, qualitatively, with 0 = glabrous (bare), 1 = puberlulent (minimal hair present, but not functionally dense), 2 = functionally-dense (but leaf surface still partially visible), to 3 = tomentose (hair obscuring the leaf surface). Stem specific density was derived from dry segments of stem two to three flushes proximal to the terminal meristem to ensure tissue had lignified. Stem segments with bark were measured for diameter, length and mass to calculate cylindrical volume and density. To calculate the Huber Value, the total leaf area was estimated from the mean leaf area of all three measured leaves, multipled by the total number of leaves distal to the stem cross-section. Blank values in the data files indicate unmeasured values.

Species mean values come from a minimum of three individuals*, collected across the species range, with a mean of 14.0 ± 12.0 (SD) leaves measured per species. The majority of leaves were field collected between 2012 and 2014, and are now held by MIN and MOR Index Herbaria. Measurements completed during 2013 and 2014. 

*28 species had fewer than three individuals: Q. affinis, ajoensis, aliena, buckleyi, canariensis, cornelius-mulleri, dalechampii, diversifolia, dumosa, dysophylla, gentryi, germana, glaucoides, gravesii, greggii, laeta, macranthera, ocoteifolia, parvula, peninsularis, polycarpa, pumila, sadleriana, sartorii, shumardii, similis, stenbergii, x acutidens

At this date, these data have been used in:
1) Kaproth, M. A., Fredericksen, B. W., González‐Rodríguez, A., Hipp, A. L., & Cavender‐Bares, J. (2023). Drought response strategies are coupled with leaf habit in 35 evergreen and deciduous oak (Quercus) species across a climatic gradient in the Americas. New Phytologist, 239(3), 888–904. https://doi.org/10.1111/nph.19019
2) Kirsch, A., & Kaproth, M. A. (2022). Defining plant ecological specialists and generalists: Building a framework for identification and classification. Ecology and Evolution, 12, e9527. https://doi.org/10.1002/ece3.9527
3) Cavender-Bares, J., Kothari, S., Meireles, J. E., Kaproth, M. A., Manos, P. S., & Hipp, A. L. (2018) The role of diversification in community assembly of the oaks (Quercus L.) across the continental U.S. American Journal of Botany 105(3): 565–586. https://doi.org/10.1002/ajb2.1049 Dryad data available: https://doi.org/10.5061/dryad.j4sf2
4) Hipp, A.L., Manos, P.S., González-Rodríguez, A., Hahn, M., Kaproth, M., McVay, J.D., Avalos, S.V., & Cavender-Bares, J. (2018), Sympatric parallel diversification of major oak clades in the Americas and the origins of Mexican species diversity. New Phytol, 217: 439-452. https://doi.org/10.1111/nph.14773
5) Kaproth, M. A. & Cavender-Bares J. (2016) Drought tolerance and climatic distributions of the American oaks. International Oaks 27:49-60 https://www.internationaloaksociety.org/content/drought-tolerance-and-climatic-distributions-american-oaks-0

Acknowledgements:
This work was funded by a UMN HHMI award to M. Kaproth & W. Pearse, as well as NSF 1146488: Phylogeny of the New World oaks: Diversification of an ecologically important clade across the tropical-temperate divide, awarded to A. Hipp, J. Cavender-Bares, P. Manos, J. Romero-Severson, A. Gonzalez-Rodriguez. We thank these researchers as well as M. Hahn, R. Smykalski, A. Scollard, S. Schnifer, S. Seramur, J. Nockwicki, B. Fredericksen, N. McMann, G. Perez, A. Ramirez and W. Pearse.

Citations noted in descriptions above or in the DRUM record abstract:

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