Chenopodium sp. 2

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 : 60-62

Chenopodium sp. 2

Text-fig. 11b

M a t e r i a l. USNM PAL 624372.

L o c a l i t y. Dakin.

D e s c r i p t i o n. Seed circular, 1.4– 1.2 mm in diameter, funicle 0.3 mm long, 0.3 mm wide, sculpture psilate.

Comments on Chenopodium

Chenopodium seeds are round with a funicle and range in sculpture from reticulate to psilate ( Benet-Pierce and Simpson 2014). A reticulate sculptured Chenopodium is known from the Miocene-Pleistocene of Tibet, however, Chenopodium sp. 1 has larger fossa in the reticulae and Chenopodium sp. 2 is psilate ( Huang et al. 2021). Modern Chenopodium seeds can be reticulate or psilate ( Benet-Pierce and Simpson 2014). Here we figure Chenopodium pratericola RYDB. ( Text-fig. 11c , Minnesota Wildflowers 2023b) and Chenopodium polyspermum L. ( Text-fig. 11d , Agricultura Romaneasca 2011) as comparisons. We also compared these two seeds to those of Corydalis DC. ( Papaveraceae ) which are of similar size, shape and may be reticulate or psilate. It would appear though that Corydalis seeds are slightly less circular and have a deeper indentation near the funicle (pers. obs.). Rutaspermum was also identified from the Kishenehn but we distinguish these Chenopodium from the Rutaspermum by their circular rather than reniform shape. Eurya THUNB. ( Theaceae ) is also reniform ( Bhandari et al. 2009). We also looked at other genera in the Chenopodioideae. Stutzia E.H. ZACHARIAS has fruiting bracts that are arrowhead shaped ( Zacharias 2012). Cycloloma fruits generally have attached, papery perianth, and although that could have worn off to leave the seed, the hilar scar is less prominent (image by Carole Ritchie, United States Department of Agriculture Natural Resource Conservation Service PLANTS Database in Vescovo 2023). Both Chenopodiastrum S. FUENTES and Cycloloma appear less coiled than Chenopodium (image by Stefan Lefnaer in Areces-Berazain 2022, image by Carole Ritchie, United States Department of Agriculture Natural Resource Conservation Service PLANTS Database in Vescovo 2023). This is not an exhaustive list of genera in Chenopodioideae but should serve to illustrate that these seeds are distinguishable from other dissiminules in the subfamily. These are the oldest recorded Chenopodium fossils.

Figures

Text-fig. 11. a: USNM PAL 624090 Chenopodium sp. 1. Scale bar 1mm. b: USNM PAL 624372 Chenopodium sp. 2. Scale bar 2mm. c: Chenopodium pratericola from Minnesota Wildflowers 2023b. d: Chenopodium hybridum, FLAS seed collection. Scale bar 1mm. e: USNM PAL 625523 Eucommia montana showing subapical stigmatic cleft, seed body and stipe. Scale bar 1mm. f: USNM PAL 625160 E. montana showing faint subapical stigmatic cleft and stipe. Scale bar 2mm. g: USNM PAL 768185 E. montana showing subapical stigmatic cleft, reticulate venation and stipe. Scale bar 2mm. h: USNM PAL 624697 Fraxinus sp. samara showing long persistent pedicel, seed body and wing. Scale bar 5mm. i: USNM PAL 625396 Catalpae seed with frayed wings. Scale bar 2mm. j: USNM PAL 624316 Catalpae seed with frayed wings. Scale bar 1mm. k: USNM PAL 722179 Apialean schizocarp with lateral spines and line of dehiscence. Scale bar 2mm.