Equisetum 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 : 40

Equisetum sp.

Text-fig. 2a

M a t e r i a l. USNM PAL 620616.

L o c a l i t y. Park.

D e s c r i p t i o n. Stem 20.8 mm long and 2.2 mm wide; 3 nodes, 2 internodes; 5–6 leaves visible per node (estimate fully 10–12 leaves per node); basal leaves 2.9 mm long, 0.5 mm wide at base, apical leaves 5.1 mm long, 0.5 mm wide at base; sheath (excluding leaves) 4.0 mm long.

R e m a r k s. Equisetum commonly grow in wet areas next to streams and ponds and is commonly preserved in the fossil record. The single specimen that we studied is noteworthy in the relatively elongate triangular leaves. Similar species include Equisetum limosum ? L. which has longer internodes ( Lesquereux 1878) and E. winchesteri BROWN from the Green River Formation of Wyoming and Colorado, but E. winchesteri is larger in width and has more leaves ( Brown 1929). Equisetum is also recognized from the early Eocene Okanagan floras of British Columbia ( Smith et al. 2012, Greenwood et al. 2016) and middle Eocene Thunder Mountain flora of Idaho ( Axelrod 1998).

Figures

Text-fig. 2. Equisetum and conifers from the Kishenehn Formation. a: USNM PAL 620616 Equisetum sp. stem apex. Scale bar 3mm. b: USNM PAL 622297 Coniferae 1. Scale bar 5mm. c: USNM PAL 622081 Coniferae 2. Scale bar 2mm. d: USNM PAL 717666 cf. Metasequoia sp. seed. Scale bar 1mm. e: USNM PAL 622101 cf. Metasequoia sp. seed. Scale bar 1mm. f: USNM PAL 776571 Metasequoia sp. twig showing opposite leaves. Scale bar 10mm g: USNM PAL 776572 Metasequoia sp. twigs. Scale bar 10 mm. h: USNM PAL 621667 Juniperus sp. leafy twig. Scale bar 5mm. i: USNM PAL 722223 Juniperus sp. twig. Scale bar 2mm. Scale bar 3mm. j: USNM PAL 623467 unidentified Cupressoideae 1. Scale bar 3mm. k: USNM PAL 620274 unidentified Cupressoidae 2 leaves. l: USNM PAL 620087 unidentified Cupressoideae 2. Scale bar 1mm. m: USNM PAL 620184 unidentified Cupresseoideae 3 shoot. Scale bar 2mm. n: USNM PAL 621863 Cupressoideae 4 leafy twig. Scale bar 5mm.