Sapindaceae

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 : 58

Sapindaceae sp.

Text-fig. 9c

M a t e r i a l. USNM PAL 625792.

L o c a l i t y. Spring.

D e s c r i p t i o n. Fruit a bladder-like capsule, elliptical, 17.2 mm tall with three wings showing, each 6.8 mm wide, divided by a line of dehiscence; seeds circular, 1.0 mm long to 0.7 mm wide; one per locule attached near the midway point between base and apex of the fruit.

This faintly preserved specimen shows quite clearly the longitudinal septum and darkened central seed attachments, but the outline of the surrounding bladder is seen only near the base and apex. The septa in Koelreuteria ( Sapindaceae ), terminate, distally about a third of the way up the fruit, where the seeds attach ( Manchester et al. 2009), so that the locular cavities join into a single locule above the seed attachment. Our specimen does not show termination in the septa. Neither Craigia W.W. SM. et W.E. EVANS ( Malvaceae ), Urvillea KUNTH ( Sapindaceae ) nor Arfeuillea PIERRE ex RADLK. ( Sapindaceae ) possess this feature of our fossil. Species of Craigia vary in length from 9–35 mm and 7–33 mm in width, are septicidal and possess wings with radiating veins ( Wang et al. 2021). Urvillea is 20–40 mm tall 15–18 mm wide (in U. venezuelensis FERRUCCI ), is septifragal, one-seeded, has subparallel veins and its veins radiate outward ( Ferrucci 2006, Wang et al. 2013, 2021). Arfeuillea is 50 mm long, 45 mm wide, is loculicidal and has net-like veins and a flat to slightly rounded apex. cf. Boniodendron is a potential candidate as the modern fruits are subglobose, 18–23 mm tall and have one seed per locule at the same level as in this fossil ( Wang et al. 2013). Boniodendron has loculicidal dehiscence ( Wang et al. 2013). Without a clear understanding of how the valves open or the venation, we are unable to assign this fossil to a genus. Based on the commonality of winged-bladder fruits in Sapindaceae , the fossil likely belongs to this family.

Figures

Text-fig. 9. a: USNM PAL 625742 Dipteronia samara showing pedicel, disc, an undeveloped fruit and a developed fruit. Scale bar 5mm. b: USNM PAL 621805 wings of cf. Boniodendron capsule. Scale bar 2mm. c: USNM PAL 625792 Sapindaceae capsular fruit with wings, septae and seeds. Scale bar 5mm. d: USNM PAL 623735 cf. Cedrela seed. Scale bar 3mm. e: USNM PAL 622276 Ailanthus confucii fruit showing seed body, ventral vein and stylar vein. Scale bar 5mm. f: USNM PAL 624113 Rutaspermum sp. Scale bar 2mm.