Typha

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 : 50-51

Genus Typha L.

Text-fig. 5d–f

M a t e r i a l. USNM PAL 729860, 621989, 622997,

623087, 623129, 623144, 717449, 625390, 625721.

L o c a l i t i e s. Dakin, Disbrow Creek, Park and Spring.

D e s c r i p t i o n. Carpodium 2.5–6.8 mm long, 0.6– 0.9 mm wide; carpodium body obovate with rounded apex, 0.6–3.5 mm long, 0.6–0.9 mm wide tapering to gynophore; gynophore 1.9–3.6 mm long, vein sometimes visible going into carpodium from gynophore; follicle cylindrical fusiform, 1.9–2.1 mm long, 0.7–0.8 mm wide; coat thin; edges straight,; one pole with small tuft (remnant style) 0.1 mm long, or rounded poles; lateral edges flat; sulcus running between poles; fruit body elongated ellipse, 1.1– 2.1 mm long, 0.3–0.7 mm wide; cylindrical projections at pole(s) gently tapering distally 0.1–0.3 mm tall, 0.1–0.2 mm wide proximally, 0.1 mm distally; single longitudinal groove; psilate sculpture.

R e m a r k s. Although the fossils are similar in shape and size to Wolffiella there is a stipe and vein in the developing Typha fruit that is not present in Wolffiella . The thin wall of the follicle can be observed in modern cattails ( Iowa Plants 2012).

This fossil bears some resemblance in shape and size to fruits of modern Elodea MICHX. ( Hydrocharitaceae ), a genus found throughout the Americas today ( Kirkbride et al. 2000, Haynes 2020). Hydrilla RICH. is similar in morphology but is smaller (less than 1 mm) and is more sculptured with longitudinal grooves ( Kirkbride et al. 2000). Similarly shaped seeds can also be found in Plantago L. ( Plantaginaceae ), which is globally distributed (except in Antarctica) ( Canadian Food Inspection Agency 2017) and in Carex sp. ( Bhandari et al. 2010, 2011). Despite similarities with Elodea , Hydrilla and Plantago , the fossil fruits have polar extensions that the aforementioned plants do not have. The lateral edges of Elodea ( Kirkbride et al. 2000, Haynes 2020) and Carex L. fruits are more rounded rather than flat, as observed ( Bhandari et al. 2010, 2011). Carex scales can be triangular but lack the polar extension and possess foliar lateral extensions near the base, which do not appear in the fossil (Minnesota Wildflowers 2023a).

Typha has been identified based on pollen from the Paleocene Fort Union Formation of Montana ( Wilson and Webster 1946) . Macrofossils of Typha and/or Sparganium are reported from the early Eocene Green River Formation of Wyoming ( Grande 1984), the Eocene Hat Creek Formation and Ootsa Lake Group of British Columbia ( Blackburn 1982, Ludvigsen 2001), the middle Eocene Thunder Mountain flora of Idaho ( Axelrod 1998) and the John Day Formation of Oregon ( Manchester 2000). Both pollen and fruits have been recovered from exposures of the Kishenehn in Canada ( Hopkins and Sweet 1976).

Figures

Text-fig. 5. Potamogeton sp. and Typha sp. from the Kishenehn Formation. a: USNM PAL 622670 Potamogeton sp. stem and leaves. Scale bar 1cm. b: DMNH EPI. 48225 Potamogeton sp. showing vegetative structures and fruit. Scale bar 1cm. c: USNM PAL 623125 Potamogeton sp. infructescence with leaves. Scale bar 5mm. d: USNM PAL 622997 follicle body of Typha sp. showing longitudinal opening and apical tuft/stylar remnant. Scale bar 1mm. e: USNM PAL 623087 follicle body of Typha sp. showing longitudinal opening. Scale bar 1mm. f: USNM PAL 621989 Typha sp. carpodium. Scale bar 2mm.