Concept
Ovule
Related concepts (24)
Sporangium
A sporangium (: sporangia; from Late Latin, ), also known as a "sporange", is an enclosure in which spores are formed. It can be composed of a single cell or can be multicellular. Virtually all plants, fungi, and many other lineages form sporangia at some point in their life cycle. Sporangia can produce spores by mitosis, but in nearly all land plants and many fungi, sporangia are the site of meiosis and produce genetically distinct haploid spores.
Pteridospermatophyta
The term Pteridospermatophyta (or "seed ferns" or "Pteridospermatopsida") is a polyphyletic wastebasket taxon of extinct seed-bearing plants (spermatophytes). The earliest fossil evidence for plants of this type is the genus Elkinsia and the Lyginopterids of late Devonian age. They flourished particularly during the Carboniferous and Permian periods. Pteridosperms declined during the Mesozoic Era and had mostly disappeared by the end of the Cretaceous Period, though Komlopteris seem to have survived into Eocene times, based on fossil finds in Tasmania.
Double fertilization
Double fertilization is a complex fertilization mechanism of flowering plants (angiosperms). This process involves the joining of a female gametophyte (megagametophyte, also called the embryo sac) with two male gametes (sperm). It begins when a pollen grain adheres to the stigma of the carpel, the female reproductive structure of a flower. The pollen grain then takes in moisture and begins to germinate, forming a pollen tube that extends down toward the ovary through the style.
Receptacle (botany)
In botany, the receptacle refers to vegetative tissues near the end of reproductive stems that are situated below or encase the reproductive organs. In angiosperms, the receptacle or torus (an older term is thalamus, as in Thalamiflorae) is the thickened part of a stem (pedicel) from which the flower organs grow. In some accessory fruits, for example the pome and strawberry, the receptacle gives rise to the edible part of the fruit. The fruit of Rubus species is a cluster of drupelets on top of a conical receptacle.