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.
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 †
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
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
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 †
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 †
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