Basal Seed Plants

Oldest known spermatophytes

The earliest preseed plants appear in the upper Middle Devonian. The preovules were small, radially symmetrical usually surrounded by a cupule. These preovules were composed of a megasporangium surrounded by an integument, but the integument was not complete. The preovule bears an unopened distal extension protruding above the multi-lobed integument, which is assumed to be involved in wind pollination.

Geologic Age

Late Devonian (Famennian) -Early Carboniferous

Systematics

└Embryophytes

└Tracheophytes

└Euphyllophytes

└Lignophytes

└Spermatophytes

Above: Late Devonian seed morphologies, a) Moresnetia-type, b) Dorinnotheca-type, c) Warsteinia-type, d) Aglosperma-type, e) Condrusia-type (from Prestianni & Gerrienne 2010 [Fig. 3])

Aglosperma †

A. quadrapartita †

  • Hilton & Edwards 1996

A. avonensis †

  • Hilton 1998

Archaeosperma arnoldii †

  • Pettitt & Beck 1968

  • Branching systems ("Moresnetia-type") bearing cupules with seeds

    • Cupule had 5-6 broad lobes

Cosmosperma polyloba †

  • Wang et al. 2014

  • Found from South China (Wutong Formation, Changxing County)

  • Cupulate ovules: one ovule surrounded by up to 16 distal segments and with minute spines on the outer surface

  • Synangiate pollen organs bearing six to eight microsporangia fused only at the base,

  • Planate and highly dissected pinnules in alternate arrangement

Condrusia †

  • Stockmans 1948

  • Seeds are enclosed in well-developed wing, composed of two flat cupule segments adpressed against each other

  • C. brevis (Petrosyan in Lepekhina et al. 1962)

  • C. minor (Stockmans 1948)

  • C. rumex (Stockmans 1948)

Dorinnotheca streelii †

  • Fairon-Demaret 1996

  • 3-4 integument lobes around nucellus

  • Cupule is large with 8 proximally-fused parts, forming a cup; distal ends divided into at least 40 free tips

  • Cupule may aid in wind dispersal

Above: Archaeosperma

Above: Reconstruction of Cosmosperma

Elkinsia polymorpha †

  • Rothwell et al. 1989, Serbet & Rothwell 1992

  • Late Devonian of West Virginia

  • Elkinsia has an unbranched stem, with pinna-bearing fronds proximally on the plant

    • Stems are terete with three-ribbed centarch protostele, maturation of other protoxylem marginally mesarch.

    • Fronds helically arranged, composed of terete rachides with papillionoid, C-shaped bundles proximally and circular bundles distally, vegetative fronds with sphenopterid pinnules

  • Distally, the plant displays "fertile cruciately forking fronds with terminal cupules or prepollen organs" (Serbet & Rothwell 1992)

    • There are four (pre)ovules born in each cupule (=cup-like branch system surrounding ovule)

    • These ovules are considered "preovules" since the integument "...does not completely surround the nucellus to form a functional micropyle" (Serbet & Rothwell 1992)

    • There are 16 sterile branch tips surrounding preovules

Guazia dongzhiensis

  • Wang et al. 2021

  • Late Devonian (Famennian) of China

  • This ovule is apparently without a cupule, unlike other Late Devonian seeds.

  • Dichotomous fertile branches bearing terminal ovules

  • Ovules elongate, obovoid, radially symmetrical and lacking a cupule

  • Four broad wing-like lobes as integumentary outgrowths cruciately arranged in each ovule, distally tapered, and proximally reduced

  • Individual integumentary lobes folding inwards along abaxial side

  • Free parts of integumentary lobes 30%-40% of ovule length

  • Nucellus present except for near apex adnate to integument

  • Nucellar apex dome-shaped.

Hydrasperma tenuis †

  • Matten et al. 1975

  • Famennian

  • The cupules containing 2–6 seeds are borne in pairs.

  • Each cupule is campanulate and composed of up to 24 oval to terete units.

  • The axis of the cupule is forked, each resultant branch dividing in an alternate monopodial fashion producing six major axes

Above: Hydrasperma reconstruction

Moresnetia zalesskyi †

  • Stockmans 1948, Fairon-Demaret and Scheckler 1987

  • Found in Belgium

  • Branching systems bearing cupules with seeds

    • Cupule had 8-10 thin lobes

Glamorgania gayerii †

  • Hilton 2006

  • "Moresnetia-type" seed

Kerrya mattenii †

  • Rothwell & Wight 1989

  • "Moresnetia-type" seed

Latisemania longshania †

  • Wang et al. 2015

  • Late Devonian (Famennian) of the Wutong Formation of China

  • Cupulate ovules that are terminal and opposite on the fertile axis

  • Associated foliage (not attached) is Sphenopteris-like

Lenlogia krystofovichii †

  • Krassilov & Zakharova 1995

  • "Moresnetia-type" seed

Pseudosporogonites hallei †

  • Stockmans 1948)

  • "Aglosperma-type" seed

Above: Reconstruction of Moresnetia

Teruelia diezii †

  • Wang et al. 2016

  • Upper Devonian (Famennian) Wutong Formation, Dongzhi County, Anhui Province, China

  • Pollen organ associated with, but not attached to, vegetative fronds

  • Fertile axes with terminal pollen organs are dichotomous for 2-4 times, and may be proximally attached by fragmentary pinnules

  • Pollen organs are synangiate and borne on the top of a short stalk

    • Synangia are radial in symmetry, and each consists of 4-8 elongate microsporangia fused at base.

    • Microsporangia have a longitudinal dehiscence line and show a tapered apex

  • The associated stem is spiny and bears a vegetative frond which bifurcates once at the basal-most part.

    • Frond rachises possess one order of pinna arranged alternately

    • Pinnules are borne alternately, planate, highly dissected, and equally dichotomous for 2-3 times.

  • Telangiopsis sp. reinforces that the Late Devonian pollen organs are synangiate usually with basally fused microsporangia.

Warsteinia paprothii †

  • Rowe 1997

  • Lacks a cupule

  • Integument is four winged lobes are fused to the nucellus

    • Possible indicator of wind, maybe water, dispersal (anemochory)

Xenotheca

X. devonica (Arber & Goode 1915; Hilton & Edwards 1999)

  • "Moresnetia"-type seed

X. bertrandii (Stockmans 1948)

  • "Aglosperma-type" seed