Were All Devonian Seeds Cupulate? A Reinvestigation ofPseudosporogonites hallei,Xenotheca bertrandii, andAglospermaspp.

Abstract

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Latisemenia longshania , gen. et sp. nov., a new Late Devonian seed plant from China

“…Latisemenia more closely resembles Pseudosporogonites [4] than any other Devonian ovules in its uniovulate and broad cupules, and in the largely exposed and similarly sized ovules with four broad integumentary lobes (table 1). However, the ovule of Pseudosporogonites is only basally surrounded by a collaret cupule without differentiation into segments, the cupule tip is not higher than the chalaza ( fig.…”

“…As in Latisemenia, Pseudosporogonites has broad integumentary lobes (although less fused), and cupules of both genera are broad but poorly developed (not overtopping the ovule); and cupules are lost in several groups of younger seed plants such as medullosans and callistophytes. A more entire integument of early ovules, such as large (long and wide) and/or extensively fused integumentary lobes as found in Dorinnotheca, Glamorgania and Pseudosporogonites, may have aided pollen capture and provided additional protection to the nucellus and water loss reduction [1,4,6,20,21,23]. Such functions of the integument appear evident in Latisemenia, with its flattened integumentary lobes that enclose the nucellus except for the apex.…”

“…While cupules of putative ovules of Cosmosperma have recently been reported from the Famennian of China [5], Latisemenia represents the first unequivocal Devonian ovules found outside Euramerica. Among the earliest seed plants from the Famennian, Latisemenia is the only one known to bear non-terminal ovulate cupules, whereas other Famennian cupules, if found attached, occur singly, in pairs, or in threes on the top of a fertile branch, which is sometimes dichotomous [1,3,4,[16][17][18][19][20][21][22][23] (table 1). Where known, these fertile branches are borne cruciately (Moresnetia and Elkinsia) or pinnately (Dorinnotheca) [19][20][21].…”

“…The palaeofloras of the two components of Laurussia have much in common, even sharing the same genus and species of ovules (e.g. Pseudosporogonites bertrandii [4]), and are known for pollen organs [43][44][45] or anatomy of seed plant branches [43,[46][47][48][49]. Recently, the Famennian Cosmosperma (cupules and pollen organs) [5], Kongshania (pollen organs) [50], Placotheca (pollen organs) [51] and Yiduxylon (vegetative branches with anatomy) [52] have been reported from South China.…”

“…The first major evolutionary radiation of seed plants (spermatophytes) occurred in the Famennian of the Late Devonian, when ovules show great diversification in the morphology and structure of integuments and cupules [1][2][3][4][5]. Sometimes, the term seed (fertilized ovule producing an embryo) instead of ovule (unfertilized organ) is used in fossil plants, although usually it is unknown if fertilization has happened [2,6].…”