Populus sp.

Smith, MacKenzie A., Greenwalt, Dale E. & Manchester, Steven R., 2023, Diverse Fruits And Seeds Of The Mid-Eocene Kishenehn Formation, Northwestern Montana, Usa, And Their Implications For Biogeography, Fossil Imprint 79 (1), pp. 37-88 : 53

Populus sp.

Text-fig. 7b

M a t e r i a l. USNM PAL 624027.

L o c a l i t y. Dakin.

D e s c r i p t i o n. Capsule 4.1 mm long, 2.8 mm wide; pedicel 5.1 mm long, 0.4 mm wide; pedicel thick at apex and base and thinner in center with a thickened scar of five detached sepals at junction with base of the fruit; threevalved ovate loculicidal capsule; apices of capsule valves slightly rounded.

R e m a r k s. Fruits of Populus wilmattae COCKERELL , P. tidwellii MANCHESTER, JUDD et HANDLEY and those associated with P. cinnamomoides (LESQ.) MACGINITIE have been described from the Green River Formation (Manchester et al. 1986, Manchester et al. 2006). Although the capsule from Kishenehn is the same in shape, valve number, dehiscence type, it is about half the size as those of P. tidwellii and P. cinnamomoides from the Green River Formation ( Manchester et al. 2006), but they conform in size with those of P. wilmattae (3–4.5 mm wide and 5 to 7 mm long; Manchester et al. 1986). Fruits of Pseudosalix handleyi L. BOUCHER , MANCHESTER et JUDD, from the Green River Formation, are somewhat larger (5.5–7.5 mm long and 3.0– 4.5 mm wide), but are similar in shape, valve number and dehiscence type. P. handleyi possesses longitudinal ribs which are absent in the Kishenehn fossil and thus the Kishenehn fossil cannot be placed in that genus ( Boucher et al. 2003). Leaves attributed to Populus have been recognized from the mid-Eocene Thunder Mountain flora of Idaho ( Axelrod 1998). Although Populus was a dominating element of the Green River flora of Colorado and Utah, only a single fruit is known from the Kishenehn collections.

Figures

Text-fig. 7. a: USNM PAL 722490 cf. Myriophyllum fruit. Scale bar 1mm. b: USNM PAL 624027 three-valved Populus sp. capsule on pedicel. Scale bar 3mm. c: USNM PAL 717328 Deviacer wolfei samara. Scale bar 5mm. d: USNM PAL 621987 Fabaceae sp. 1 Legume fruit showing persistent style. Scale bar 2mm. e: USNM PAL 625803 Fabaceae sp. 2 fruit. Scale bar 5mm. f: USNM PAL 620816 Agrimonia sp. fruit. Scale bar 3mm. g: Modern Agrimonia pubescens fruit (image by Tracey Slotta, United States Department of Agriculture National Resource Conservation Service Plants Database). h: USNM PAL 621976 Ulmus sp. F1 fruit showing two persistent styles. Scale bar 2mm. i: DMNH EPI.48205 Ulmus sp. L1 leaf. Scale bar 1cm. j: UF 19652-86483 endocarp of Celtis sp. k: UF 19652-86484 Endocarps of Celtis sp.