A spermatophyte (; ), also known as phanerogam (taxon Phanerogamae) or phaenogam (taxon Phaenogamae), is any
plant that produces
seeds, hence the alternative name seed plant. Spermatophytes are a subset of the
embryophytes or land plants. They include most familiar types of plants, including all
flowers
A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants (plants of the division Angiospermae). The biological function of a flower is to facilitate reproduction, usually by providing a mechanism ...
and most
trees, but exclude some other types of plants such as
ferns
A fern (Polypodiopsida or Polypodiophyta ) is a member of a group of vascular plants (plants with xylem and phloem) that reproduce via spores and have neither seeds nor flowers. The polypodiophytes include all living pteridophytes except th ...
,
mosses,
algae
Algae (; singular alga ) is an informal term for a large and diverse group of photosynthesis, photosynthetic eukaryotic organisms. It is a polyphyletic grouping that includes species from multiple distinct clades. Included organisms range from u ...
.
The term ''phanerogams'' or ''phanerogamae'' is derived from the
Greek (), meaning "visible", in contrast to the
cryptogamae
A cryptogam (scientific name Cryptogamae) is a plant (in the wide sense of the word) or a plant-like organism that reproduces by spores, without flowers or seeds. The name ''Cryptogamae'' () means "hidden reproduction", referring to the fact ...
(), together with the
suffix (), meaning "to marry". These terms distinguished those plants with hidden sexual organs (cryptogamae) from those with visible sexual organs (phanerogamae).
Description
The extant spermatophytes form five divisions, the first four of which are traditionally grouped as
gymnosperms, plants that have unenclosed, "naked seeds":
*
Cycadophyta
Cycads are seed plants that typically have a stout and woody ( ligneous) trunk with a crown of large, hard, stiff, evergreen and (usually) pinnate leaves. The species are dioecious, that is, individual plants of a species are either male or ...
, the cycads, a subtropical and tropical group of plants,
*
Ginkgophyta, which includes a single living species of tree in the genus ''
Ginkgo'',
*
Pinophyta
Conifers are a group of cone-bearing seed plants, a subset of gymnosperms. Scientifically, they make up the division Pinophyta (), also known as Coniferophyta () or Coniferae. The division contains a single extant class, Pinopsida. All exta ...
, the conifers, which are
cone-bearing trees and shrubs, and
*
Gnetophyta, the gnetophytes, various woody plants in the relict genera ''
Ephedra'', ''
Gnetum
''Gnetum'' is a genus of gymnosperms, the sole genus in the family Gnetaceae within the Gnetophyta. They are tropical evergreen trees, shrubs and lianas. Unlike other gymnosperms, they possess vessel elements in the xylem. Some species have been ...
'', and ''
Welwitschia
''Welwitschia'' is a monotypic gymnosperm genus, comprising solely the distinctive ''Welwitschia mirabilis'', endemic to the Namib desert within Namibia and Angola. ''Welwitschia'' is the only living genus of the family Welwitschiaceae and or ...
''.
The fifth extant division is the
flowering plants, also known as angiosperms or magnoliophytes, the largest and most diverse group of spermatophytes:
*
Angiosperms
Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek words ('container, vessel') and ('seed'), and refers to those plants th ...
, the flowering plants, possess seeds enclosed in a
fruit, unlike gymnosperms.
In addition to the five living taxa listed above, the fossil record contains evidence of many
extinct taxa of seed plants, among those:
*
Pteridospermae
The term Pteridospermatophyta (or "seed ferns" or "Pteridospermatopsida") is a polyphyletic group of extinct seed-bearing plants (spermatophytes). The earliest fossil evidence for plants of this type is the genus ''Elkinsia'' of the late Devonian ...
, the so-called "seed ferns", were one of the earliest successful groups of land plants, and forests dominated by seed ferns were prevalent in the late
Paleozoic.
* ''
Glossopteris
''Glossopteris'' tymology: from Ancient Greek γλῶσσα (glôssa, " tongue ") + πτερίς (pterís, " fern ")is the largest and best-known genus of the extinct Permian order of seed ferns known as Glossopteridales (also known as Arberia ...
'' was the most prominent tree genus in the ancient southern supercontinent of
Gondwana during the
Permian period.
By the
Triassic
The Triassic ( ) is a geologic period and system which spans 50.6 million years from the end of the Permian Period 251.902 million years ago ( Mya), to the beginning of the Jurassic Period 201.36 Mya. The Triassic is the first and shortest period ...
period, seed ferns had declined in ecological importance, and representatives of modern gymnosperm groups were abundant and dominant through the end of the
Cretaceous, when the
angiosperms
Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek words ('container, vessel') and ('seed'), and refers to those plants th ...
radiated.
Evolutionary history
A
whole genome duplication event in the ancestor of seed plants occurred about .
[Jiao Y, Wickett NJ, Ayyampalayam S, Chanderbali AS, Landherr L, Ralph PE, Tomsho LP, Hu Y, Liang H, Soltis PS, Soltis DE, Clifton SW, Schlarbaum SE, Schuster SC, Ma H, Leebens-Mack J, Depamphilis CW (2011) Ancestral polyploidy in seed plants and angiosperms. Nature] This gave rise to a series of evolutionary changes that resulted in the origin of seed plants.
A middle
Devonian (385-million-year-old)
precursor to seed plants from
Belgium has been identified predating the earliest seed plants by about 20 million years. ''
Runcaria'', small and radially symmetrical, is an integumented
megasporangium surrounded by a cupule. The
megasporangium bears an unopened distal extension protruding above the mutlilobed
integument
In biology, an integument is the tissue surrounding an organism's body or an organ within, such as skin, a husk, shell, germ or rind.
Etymology
The term is derived from ''integumentum'', which is Latin for "a covering". In a transferred, or ...
. It is suspected that the extension was involved in anemophilous (wind)
pollination. ''Runcaria'' sheds new light on the sequence of character acquisition leading to the seed. ''Runcaria'' has all of the qualities of seed plants except for a solid
seed coat and a system to guide the pollen to the seed.
Relationships and nomenclature
Seed-bearing plants are a
subclade
In genetics, a subclade is a subgroup of a haplogroup.
Naming convention
Although human mitochondrial DNA (mtDNA) and Y chromosome DNA (Y-DNA) haplogroups and subclades are named in a similar manner, their names belong to completely separate sys ...
of the
vascular plants
Vascular plants (), also called tracheophytes () or collectively Tracheophyta (), form a large group of land plants ( accepted known species) that have lignified tissues (the xylem) for conducting water and minerals throughout the plant. They a ...
(tracheophytes) and were traditionally divided into
angiosperm
Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek words ('container, vessel') and ('seed'), and refers to those plants th ...
s, or flowering plants, and
gymnosperms, which includes the gnetophytes, cycads, ginkgo, and conifers. Older morphological studies believed in a close relationship between the gnetophytes and the angiosperms,
in particular based on
vessel element
A vessel element or vessel member (also called trachea or xylem vessel) is one of the cell types found in xylem, the water conducting tissue of plants. Vessel elements are typically found in angiosperms (flowering plants) but absent from most gy ...
s. However, molecular studies (and some more recent morphological and fossil papers) have generally shown a
clade of
gymnosperms, with the gnetophytes in or near the conifers. For example, one common proposed set of relationships is known as the ''gne-pine hypothesis'' and looks like:
However, the relationships between these groups should not be considered settled.
Other classifications group all the seed plants in a single
division, with
classes for the five groups:
*Division Spermatophyta
**
Cycad
Cycads are seed plants that typically have a stout and woody ( ligneous) trunk with a crown of large, hard, stiff, evergreen and (usually) pinnate leaves. The species are dioecious, that is, individual plants of a species are either male or ...
opsida, the cycads
**
Ginkgoopsida, the ginkgo
**
Pinopsida
Conifers are a group of cone-bearing seed plants, a subset of gymnosperms. Scientifically, they make up the division Pinophyta (), also known as Coniferophyta () or Coniferae. The division contains a single extant class, Pinopsida. All extan ...
, the conifers, ("Coniferopsida")
**
Gnetopsida
Gnetophyta () is a division of plants (alternatively considered the subclass Gnetidae or order Gnetales), grouped within the gymnosperms (which also includes conifers, cycads, and ginkgos), that consists of some 70 species across the three rel ...
, the gnetophytes
**
Magnoliopsida
Magnoliopsida is a valid botanical name for a class of flowering plants. By definition the class will include the family Magnoliaceae, but its circumscription can otherwise vary, being more inclusive or less inclusive depending upon the classif ...
, the
flowering plants, or Angiospermopsida
A more modern classification ranks these groups as separate divisions (sometimes under the Superdivision Spermatophyta):
*
Cycad
Cycads are seed plants that typically have a stout and woody ( ligneous) trunk with a crown of large, hard, stiff, evergreen and (usually) pinnate leaves. The species are dioecious, that is, individual plants of a species are either male or ...
ophyta, the cycads
*
Ginkgophyta, the ginkgo
*
Pinophyta
Conifers are a group of cone-bearing seed plants, a subset of gymnosperms. Scientifically, they make up the division Pinophyta (), also known as Coniferophyta () or Coniferae. The division contains a single extant class, Pinopsida. All exta ...
, the conifers
*
Gnetophyta, the gnetophytes
*
Magnoliophyta
Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek words ('container, vessel') and ('seed'), and refers to those plants t ...
, the
flowering plants
An alternative phylogeny of spermatophytes based on the work by Novíkov & Barabaš-Krasni 2015 with plant taxon authors from Anderson, Anderson & Cleal 2007
showing the relationship of extinct clades.
Unassigned spermatophytes:
* †
Avatiaceae Anderson & Anderson 2003
* †
Axelrodiopsida Anderson & Anderson
* †
Alexiales Anderson & Anderson 2003
* †
Hamshawviales Anderson & Anderson 2003
* †
Hexapterospermales Doweld 2001
* †
Hlatimbiales Anderson & Anderson 2003
* †
Matatiellales Anderson & Anderson 2003
* †
Petriellales Taylor et al. 1994
* †
Arberiopsida Doweld 2001
* †
Czekanowskiales Taylor et al. 2008
* †
Iraniales E. Taylor et al. 2008
* †
Vojnovskyales E. Taylor et al. 2008
* †
Hermanophytales E. Taylor et al. 2008
* †
Dirhopalostachyaceae E. Taylor et al. 2008
References
Bibliography
* , in
*
*
{{Authority control
Superphyla
Devonian first appearances
Plants