G L O S S A R Y

Angiosperm: A flowering plant, which forms seeds inside a protective chamber called an ovary.

Anther: The terminal pollen sac of a stamen, inside which pollen grains with male gametes form in the flower of an angiosperm.

Antheridium: In plants, the male gametangium, a moist chamber in which gametes develop.

Aperture: Any of the various modifications in the exine of spores and pollen that can be a locus for exit of the contents.

Archegonium: In plants, the female gametangium, a moist chamber in which gametes develop.

Autotroph: An organism that obtains food molecules without eating other organisms.

Bryophytes: The mosses, liverworts, and hornworts; a group of of nonvascular plants that inhabit the land but lack many of the terrestrial adaptations of vascular plants.

Carpel: The female reproductive organ of a flower, consisting of the stigma, style, and ovary.

Colpus: A longitudinal furrow- or groove-like modification in the exine of pollen grains; associated with germination.

Columella: One of the rod-like protrusion of ektexine that may branch and/or fuse distally to produce a tectum on pollen grains with complex exine structure.

Desiccation: A method of preserving organic material by the removal of its water content.

Diploid Cell: A cell containing two sets of chromosomes (2n), one set inherited from each parent.

Ektexine: Outer layer of the two layers of the exine of spores and pollen, normally more densely or deeply staining that the endexine, and characterized by richly detailed external sculpture. 

Embryo sac: The female gametophyte of angiosperms, formed from the growth and division of the megaspore into a multicellular structure with eight haploid nuclei.

Embryophytic: Of plants producing 2N (diploid) embryo as part of a 1N-2N life cycle.

Endexine: The inner, usually homogeneous layer of the two layers of the exine of spores and pollen.

Eukaryote: An organism consisting of cells in which the genetic material is contained within a distinct nucleus.

Exine: The outer, very resistant layer of the two major layers forming the wall of spores and pollen, consisting principally of sporopollenin, and situated immediately outside the intine.

Furrow: A colpus or sulcus.

Gamete: A haploid egg or sperm cell; gametes unite during sexual reproduction to produce a diploid zygote.

Gametophyte: The multicellular haploid form in organisms undergoing alternation of generations, which mitotically produces haploid gametes that unite and grow into the sporophyte generation.

Gymnosperm: A vascular plant that bears naked seeds not enclosed in any specialized chambers.

Haploid Cell: A cell containing only one set of chromosome (n).

Heterosporous: Referring to plants in which the sporophyte produces two kinds of spores that develop into unisexual gametophytes, either female or male.

Homosporous: Referring to plants in which a single type of spore develops into a bisexual gametophyte having both male and female sex organs.

Intine: The thin, inner layer of the two major layers forming the wall of spores and pollen, composed of cellulose and pectates, and situated inside the exine, surrounding the living cytoplasm.

Isodiametric: Of equal diameter.

Isospore: A spore of plants producing only one kind of spores. Syn. homospore.

Megagametophyte: The female gametophyte or haploid generation that develops from the megaspore of a heterosporous embryophytic plant.

Megaspore: (a) One of the spores of a heterosporous embryophytic plant that germinates to produce a megagametophyte.(b) A term arbitrarily defined in paleopalynology as a spore (or pollen grain) greater that 200μm in diameter.

Meiosis: A two-stage type of cell division in sexually reproducing organisms that results in gametes with half the chromosome number of the original cell.

Microgametophyte: The male gametophyte or haploid generation that develops from the microspore of a heterosporous embryophytic plant.

Microspore: One of the spores of a heterosporous embryophytic plant that germinates to produce a microgametophyte.

Mitosis: A process of nuclear division in eukaryotic cells conventionally divided into five stages: prophase, prometaphase, metaphase, anaphase, and telophase. Mitosis conserves chromosome number by equally allocating replicated chromosomes to each of the daughter nuclei.

Nexine: The inner layer of the exine of pollen in Erdtman's scheme.

Ovary: In flowers, the portion of a carpel in which the egg-containing ovule develop.

Ovule: A structure that develops in the plant ovary and contains the female gametophyte.

Photosynthesis: The conversion of light energy to chemical energy that is stored in glucose or other organic compounds; occurs in plants, algae, and certain prokaryotes.

Pollen: The mass of grains containing the male gametes of seed plants, which are produced in large number in the pollen sacs.

Pore: One of the external more or less circular or slightly oval thinnings or openings in the exine of pollen grains.

Sexine: The more or less arbitrarily delimited outer division of the exine of pollen.

Spore: A reproductive cell resistant to environmental conditions that can develop into an individual without first fusing with another reproductive cell. Spores are produced by some plants, fungi, bacteria, and some protozoa.

Sporophyte: The multicellular diploid form in organisms undergoing alternation of generations that results from a union of gametes and that meiotically produces haploid spores that grow into the gametophyte generation.

Stamen: The pollen-producing male reproductive organ of a flower, consisting of an anther and filament.

Stigma: The glandular sticky surface at the tip of a carpel of a flower.

Sulcus: An elongate aperture (furrow), in the exine of pollen grains.

Tectum: The surface of tectate pollen grains.

Vascular Plants: Plants with vascular tissue, consisting of all modern species except the mosses and their relatives.

Vascular Tissue: Plant tissue consisting of cells joined in tubes that transport water and nutrients throughout the plant body.

Zygote: The diploid product of the union of haploid gametes in conception; a fertilized egg.