Gymnosperm

Information about Gymnosperm

Gymnospermae
Enlarge picture
White Spruce leaves (needles)

White Spruce leaves (needles)
Scientific classification
Kingdom:Plantae
Divisions


Pinophyta (or Coniferophyta) - Conifers
Ginkgophyta - Ginkgo
Cycadophyta - Cycads
Gnetophyta - Gnetum, Ephedra, Welwitschia


The gymnosperms (Gymnospermae) are a group of spermatophyte seed-bearing plants with ovules on the edge or blade of an open sporophyll, the sporophylls usually arranged in cone-like structures. The other major group of seed-bearing plants, the angiosperms, have ovules enclosed in a carpel, a sporophyll with fused margins. The term gymnosperm comes from the Greek word gumnospermos, meaning "naked seeds" and referring to the unenclosed condition of the seeds, as when they are produced they are found naked on the scales of a cone or similar structure.

Gymnosperms are heterosporous, producing microspores that develop into pollen grains and megaspores that are retained in an ovule. After fertilization (joining of the micro- and megaspore), the resulting embryo, along with other cells comprising the ovule, develops into a seed. The seed is a sporophyte resting stage.

Enlarge picture
Coast Douglas-fir cone
In early classification schemes, the gymnosperms (Gymnospermae) "naked seed" plants were regarded as a "natural" group. However, certain fossil discoveries suggest that the angiosperms evolved from a gymnosperm ancestor, which would make the gymnosperms a paraphyletic group if all extinct taxa are included. Modern cladistics only accepts taxa that are monophyletic, traceable to a common ancestor and inclusive of all descendants of that common ancestor. So, while the term 'gymnosperm' is still widely used for non-angiosperm seed-bearing plants, the plant species once treated as gymnosperms are usually distributed among four groups, which can be given equal rank as divisions within the Kingdom Plantae.

With regard to extant gymnosperms, molecular phylogenies of living taxa have conflicted with morphological datasets with regard to whether they comprise a monophyletic or paraphyletic group with respect to angiosperms. At issue is whether the Gnetophyta are the sister taxon to angiosperms, or whether they are sister to, or nested within, other extant gymnosperms.

References

  • Bowe, L. Michelle, Gwénaële Coat, and Claude W. dePamphilis. 2000. Phylogeny of seed plants based on all three genomic compartments: Extant gymnosperms are monophyletic and Gnetales' closest relatives are conifers. Proceedings of the National Academy of Sciences 97: 4092-4097 (abstract).
  • Soltis, Douglas E., Pamela S. Soltis and Michael J. Zanis. 2002. Phylogeny of seed plants based on evidence from eight genes. American Journal of Botany 89: 1670-1681 (abstract).
  • Chaw, Shu-Miaw, Christopher L. Parkinson, Yuchang Cheng, Thomas M. Vincent, and Jeffrey D. Palmer. 2000. Seed plant phylogeny inferred from all three plant genomes: Monophyly of extant gymnosperms and origin of Gnetales from conifers. Proceedings of the National Academy of Sciences 97: 4086-4091 (abstract).

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Botany
Subdisciplines of botanyEthnobotany Paleobotany Plant anatomy Plant ecology Plant morphology Plant physiology
PlantsEvolutionary history of plants Algae Bryophyte Pteridophyte Gymnosperm Angiosperm
Plant partsFlower Fruit Leaf Meristem Root Stem Stoma Vascular tissue Wood
Plant cellsCell wall Chlorophyll Chloroplast Photosynthesis Plant hormone Plastid Transpiration
Plant life cyclesGametophyte Plant sexuality Pollen Pollination Seed Spore Sporophyte
Botanical nomenclatureBotanical name Herbarium IAPT ICBN Species Plantarum
Project
P. glauca

Binomial name
Picea glauca
(Moench) Voss

The White Spruce (Picea glauca
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Scientific classification or biological classification is a method by which biologists group and categorize species of organisms. Scientific classification also can be called scientific taxonomy, but should be distinguished from folk taxonomy, which lacks scientific basis.
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Plantae
Haeckel, 1866[1]

Divisions

Green algae
  • Chlorophyta
  • Charophyta
Land plants (embryophytes)
  • Non-vascular land plants (bryophytes)

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division.

The main plant divisions, in the order in which they probably evolved, are the liverworts (Division Marchantiophyta), the hornworts (Division Anthocerophyta), the mosses (Division Bryophyta), the ferns (Division Filicophyta), the horsetails (Division Sphenophyta),
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Pinophyta

Class: Pinopsida

Orders & Families

Cordaitales †
Pinales
  Pinaceae - Pine family
  Araucariaceae - Araucaria family
  Podocarpaceae - Yellow-wood family
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Ginkgoaceae

Genus: Ginkgo

Species
G. biloba L.
The Ginkgo (Ginkgo biloba; '銀杏' in Chinese), frequently misspelled as "Gingko", and also known as the
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Cycadophyta

Class: Cycadopsida

Order: Cycadales
Dumortier

Families

Cycadaceae cycas family
Stangeriaceae stangeria family
Zamiaceae zamia family

Cycads
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Gnetophyta

Class: Gnetopsida

Orders
  • Gnetales
  • Welwitschiales
  • Ephedrales


The plant division Gnetophyta
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Divisions
  • Pinophyta
  • Cycadophyta
  • Ginkgophyta
  • Gnetophyta
  • Magnoliophyta
The spermatophytes (from the Greek word "Σπερματόφυτα") (also known as phanerogams
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Plantae
Haeckel, 1866[1]

Divisions

Green algae
  • Chlorophyta
  • Charophyta
Land plants (embryophytes)
  • Non-vascular land plants (bryophytes)

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Ovule literally means "small egg." In seed plants, the ovule is the structure that gives rise to and contains the female reproductive cells. It consists of three parts: The integuments forming its outer layer, the nucellus
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A sporophyll is a leaf that produces spores. Sporophylls are part of the diploid sporophyte generation, and the spores are produced by meiosis and will germinate to produce haploid gametophytes.
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Magnoliophyta

Classes

Magnoliopsida - Dicots
Liliopsida - Monocots

The flowering plants or angiosperms are the most widespread group of land plants. The flowering plants and the gymnosperms comprise the two extant groups of seed plants.
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carpel is the outer, often visible part of the female reproductive organ of a flower; the basic unit of the gynoecium.

Carpel anatomy

The parts of the carpel are:
  • the stigma (from Ancient Greek stigma

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spore is a reproductive structure that is adapted for dispersion and surviving for extended periods of time in unfavorable conditions. Spores form part of the life cycles of many plants, algae, fungi and some protozoans.
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Pollen is a fine to coarse powder consisting of microgametophytes (pollen grains), which produce the male gametes (sperm cells) of seed plants. The pollen grain with its hard coat protects the sperm cells during the process of their movement between the stamens
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In phylogenetics, a group of organisms is said to be paraphyletic (Greek para = near and phyle = race) if the group contains its most recent common ancestor, but does not contain all the descendants of that ancestor.
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Cladistics is a philosophy of classification that arranges organisms only by their order of branching in an evolutionary tree and not by their morphological similarity, in the words of Luria et al. (1981).
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In phylogenetics, a group is monophyletic (Greek: "of one race") if it consists of an inferred common ancestor and all its descendants. A taxonomic group that contains organisms but not their common ancestor is called polyphyletic, and a group that contains some but not all
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phylogenetics (Greek: phyle = tribe, race and genetikos = relative to birth, from genesis = birth) is the study of evolutionary relatedness among various groups of organisms (e.g., species, populations).
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Gnetophyta

Class: Gnetopsida

Orders
  • Gnetales
  • Welwitschiales
  • Ephedrales


The plant division Gnetophyta
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Proceedings of the National Academy of Sciences of the United States of America, usually referred to as PNAS, is the official journal of the United States National Academy of Sciences.
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Botany is the scientific study of plant life. As a branch of biology, it is also called plant science(s), phytology, or plant biology. Botany covers a wide range of scientific disciplines that study plants, algae, and fungi including: structure, growth,
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Ethnobotany is the study of the relationship between plants and people: From"ethno" - study of people and "botany" - study of plants. Ethnobotany is considered a branch of ethnobiology. Ethnobotany studies the complex relationships between (uses of) plants and cultures.
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Paleobotany, also spelled as palaeobotany (from the Greek words paleon = old and "botany", study of plants), is the branch of paleontology or paleobiology dealing with the recovery and identification of plant remains from geological contexts, and their use for the
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Plant anatomy or phytotomy is the general term for the study of the internal structure of plants. While originally it included plant morphology, which is the description of the physical form and external structure of plants, since the mid Twentieth Century the investigation
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Ecology (also known as Oekologie, Okology, or Oekology[1],from Greek: οίκος, oikos, "household"; and λόγος, logos
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Plant morphology (or phytomorphology) is the general term for the study of the morphology (physical form and external structure) of plants.[1] This is usually considered distinct from plant anatomy, which is the study of the internal structure of plants,
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Plant physiology is a subdiscipline of botany concerned with the function, or physiology, of plants.[1] Closely related fields include plant morphology (structure of plants), plant ecology (interactions with the environment), phytochemistry (biochemistry of plants), cell
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Plantae
Haeckel, 1866[1]

Divisions

Green algae
  • Chlorophyta
  • Charophyta
Land plants (embryophytes)
  • Non-vascular land plants (bryophytes)

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