Thlaspi
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publication ID |
https://doi.org/ 10.37520/fi.2023.004 |
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persistent identifier |
https://treatment.plazi.org/id/4D2487A3-EF48-8274-FEC4-FA606BD6FA95 |
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treatment provided by |
Felipe |
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scientific name |
Thlaspi |
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Genus Thlaspi View in CoL View at ENA L.
Text-fig. 10a–h View Text-fig
M a t e r i a l. USNM PAL 622306, 623124, 623138 and
DMNH EPI.41847, 48190, 48216, 48222, 48239.
L o c a l i t y. Disbrow Creek.
D e s c r i p t i o n. Winged capsular fruit 14.3 mm long, 9.2 mm wide; pedicel 2.9 mm long; pedicel truncated; wing elliptical to ovate, with a rounded base and emarginate apex; approximately 2.5 mm between edge of central body and wing margin; fimbrial vein present; veins arise between 38– 46°. Arching apically about half-way, occasional bifurcations with the apical vein retaining the same thickness; veins lose thickness towards margin; central locular area thicker/darker than surrounding wing, fusiform, 7.2 mm long, 3.1 mm wide with longitudinal groove, slit or suture running the entire length; persistent styles 1.3 mm long; wing surrounds two styles.
R e m a r k s. We considered various candidate families for the identification of these winged fruits before settling on the assignment to Thlaspi in the Brassicaceae . The fossils are distinctive in the presence of a central body, persistent styles and arching veins of the wings. The dispersed valves of Koelreuteria LAXM. ( Sapindaceae ) and Craigia W.W. SM. et W.E. EVANS ( Malvaceae ) capsular fruits also have bilateral symmetry and are known from Eocene deposits of North America ( Kvaček et al. 2005, Wang et al. 2013). Craigia can be distinguished from Koelreuteria by the presence of a fusiform central locule in the former ( Wang et al. 2013). Two species of Craigia are currently recognized, Craigia bronnii (UNGER) KVAČEK, BŮŽEK et MANCHESTER from Europe and western Asia and Craigia oregonensis (ARNOLD) KVAČEK, BŮŽEK et MANCHESTER from North America and Asia ( Kvaček et al. 2005). These fruits have straight veins that do not lose gauge towards the wing margin unlike the fossil ( Kvaček et al. 2005). We also considered the families Begoniaceae C. AGARDH and Polygonaceae JUSS. The sides of the proximal portion of the central body in Begonia L. is detached from the wing but the overall shape is obovate and there is persistent stamen and style ( Manchester and O’Leary 2010). The wings on polygonaceous fruit are derived from the perianth and possess thin veins ( Manchester and O’Leary 2010).
The venation pattern, locule shape, persistent pedicel and style of these specimens are consistent with the previously described fossil Thlaspi primaevum H.F. BECKER from the early Oligocene Ruby flora from western Montana ( Becker 1961, Beilstein et al. 2010). We also compared the specimen to Noccaea MOENCH but the veins of that genus are less defined than those in Thlaspi . The wings of Thlaspi primaevum do not fully surround the stylar area and the perianth scars are more pronounced ( Becker 1961, Manchester and O’Leary 2010). This fossil from the Kishenehn is the oldest occurrence of Thlaspi . It would imply still an earlier radiation of the clade that includes Arabidopsis ( Beilstein et al. 2010) . The type species, T. arvense L., has a similar wing morphology, with the wings encompassing the stylar area, though the central body appears to be proportionally wider.
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