Limnobiophyllum scutatum (DAWSON) KRASSILOV

Manchester, Steven R., 2014, Revisions To Roland Brown’S North American Paleocene Flora, Acta Musei Nationalis Pragae Series B 70 (3 - 4), pp. 153-210 : 159-161

Limnobiophyllum scutatum (DAWSON) KRASSILOV

Brown (1962) agreed with the concept of Hantke (1954) that the fossil species, Hydromystria expansa (HEER) HANTKE included two morphologically distinct kinds of foliage, firstly the thin, orbicular peltate leaves that Dawson had called Spirodela scutata and secondly a thick kidney-shaped structure interpreted as float leaves which were later called Porosia verrucosa HICKEY ( Hickey 1977, emended by Manchester and Kodrul 2014). The orbicular, thin, leaves were subsequently reassigned to a new extinct genus, Limnobiophyllum by Krassilov (1973 1976) who recognized the same species in the Paleocene of E Asia). Limnobiophyllum scutatum (DAWSON) KRASSILOV was proven to represent Araceae-Lemnaceae based on specimens with attached flowers containing stamens with pollen (Stockey et al. 1997), whereas the Porosia structures, mentioned again below, have turned out to represent unrelated single-seeded dicotyledonous fruits of possible rutaceous affinity as revealed by permineralized specimens ( Manchester and Kodrul 2014).

Zingiberales

The leaf attributed to Canna? magnifolia KNOWLTON ( Brown 1962, pl. 15, fig. 2) was transferred to Zingiberopsis isonervosa HICKEY by Hickey and Petersen (1978), and considered to represent Zingiberaceae . Zingiberites dubius LESQUEREUX is based on a fragmentary specimen from the Denver Formation was that reexamined by Brown, but no additional Paleocene specimens have been recovered for more detailed evaluation.

Ensete goldianum (LESQUEREUX) comb. nov.

Text-figs 3.1, 3.2

1878 Viburnum goldianum LESQUEREUX, Rept. U. S. Geol. Surv. Terr. , 7, p. 227, pl. 60, figs 2, 2a-c (holotype and basionym).

This species, based on a grouping of seed impressions preserving both internal and external details, also represents Zingiberales . These smooth, subelliptical seeds with a truncate apex show an opercular collar similar to the configuration in extant and fossil Ensete . Although the chalazal chamber is not preserved in the casts, there is an axial perforation of the seedcoat at the base similar to that seen in extant Ensete . These resemble those described from better-preserved permineralized specimens from the Eocene of Oregon ( Manchester and Kress 1993).

Other monocots

Haemanthophyllum sp. 3 . sensu Golovneva (1997). Brown (1962) assigned leaves to Alismaphyllites grandifolius (PENHALLOW) R. W. BROWN , using the generic Alismaphyllites KNOWLTON (1917) based on specimens from the Raton Formation near Trinidad, Colorado ( Knowlton 1917, p. 286, pI. 55, fig. 1). The original specimen of Alismaphyllites crassifolium KNOWLTON (1917) , the type species of Alismaphyllites , was a stem with three attached broad monotyledonous leaves, but the venation is not sufficiently preserved for detailed comparison with the leaves later assigned to Haemanthophyllum . Golovneva (1997) designated the illustrated specimens of Brown (1962) as “ Haemanthophyllum sp. 3 .” Golovneva (1997) studied various extant families with foliage similar to Haemanthophyllum , e.g., Alismataceae , Potamogetonaceae and Aponogetonaceae . She concluded that Aponogetonaceae was more probable as to its affinities, but, also stated “The most similar to Haemanthophyllum , the alismatacean genus Caldesia , has smaller leaves.” So far, the reproductive organs of this plant remain unknown.

“ Sagittaria” megasperma R. W. BROWN ( Text-figs 3.3–3.5 ) is based on globose infructescences of winged fruits. The distinctive leaves of Sagittaria have not been observed. The winged fruits show a single style and asymmetrical to less commonly symmetrical wing development. The seed body is covered by closely spaced longitudinal veins. The wings have longitudinal veins unlike modern species of Sagittaria , so the affinities of this distinctive plant are uncertain.

The globose infructescences that Brown (1962) referred to Sparganium antiquum (NEWBERRY) BERRY are not monocots but instead represent Platanaceae . They were found at the same locality (USGS 2416) as Macginitiea nobilis .

Ceratophyllaceae

Ceratophyllum furcatispinum HERENDEEN, LES et DILCHER

Among the unidentified specimens curated in the USGS collections by Brown, but not included in his publication, were spiny fruits subsequently identified as those of Ceratophyllum ( Herendeen et al 1990). Several specimens of Ceratophyllum furcatispinum HERENDEEN, LES et DILCHER were cited, all from a single locality in Montana.

Menispermaceae

Fruits found in Paleocene strata of North Dakota and Wyoming subsequent to the publication of Brown’s monograph confirm the presence of Menispermaceae . Horseshoe-shaped endocarps have been described from Almont, North Dakota, as cf. Canticocculus CHANDLER ( Crane et al. 1990, fig. 5A–C) and as Palaeoluna sp. from Linch, Wyoming (Fig. 17 in Herrera et al. 2011). Corresponding leaves remain elusive. Those that Hickey (1977) regarded as Menispermaceae , i.e., “ Cocculus ” flabella (NEWBERRY) J. WOLFE and Menispermites parvareolatus HICKEY , were subsequently transferred to Zizyphoides SEWARD et CONWAY , and probably belonging to same plant as Nordenskioeldia fruits ( Crane et al. 1991).

Sabiaceae

The presence of Sabiaceae is confirmed on the basis of distinctive well preserved endocarps of Meliosma rostellata (LESQUEREUX) CRANE , MANCHESTER et DILCHER at Almont, North Dakota, and Golden, Colorado. The corresponding leaves, however, remain uncertain. Meliosma today can have either serrate or entire-margined leaves, and pinnate venation with well organized percurrent tertiary venation and orthogonal higher order venation, and such leaves are known from the Eocene of Oregon ( Chaney and Sanborn 1933, Manchester 1981). Hickey (1977) applied the name Meliosma longifolia (HEER) HICKEY to some of the same leaves that had earlier been called Quercus sullyi by Brown (1962); however, the specimens illustrated by Hickey, and most of those treated as Q. sullyi by Brown, instead appear to represent the extinct genus Dyrana GOLOVNEVA (1994, Budantsev and Golovneva 2009). The rounded sinuses and glandular (rather than spinose) teeth may indicate that they represent Platanaceae , rather than Sabiaceae .

Nelumbonaceae

Among the several aquatic angiosperms recognized by Brown, Nelumbium montanum R. W. BROWN , Nelumbium tenuifolium LESQUEREUX , and Paleonelumbo macroloba KNOWLTON are peltate leaves that appear to be related to extant Nelumbo . An excellent specimen of Paleonelumbo macroloba was figured by Barclay et al. (2003, figs 9a–c).

Figures

Text-fig. 3. 1, 2. Ensete goldianum (LESQUEREUX) comb. nov, Holotype, USNM 494, Golden Colorado. 1. Numerous seeds on a slab. 2. Detail of seed molds and casts. 3-5 “Sagittaria” megasperma R. W. BROWN. 3. Infructescence head. USNM 167488, lectotype selected by Watt 1971. 4. Isolated fruit showing veins of wing, and longitudinally striate central body and single style, USNM 313282, 5. Additional isolated fruit, USNM 313283. Images 4, 5 light-dark inverted. Scale = 1 cm.