Search results
Results from the WOW.Com Content Network
Whether spores arose before or after land plants, their contributions to topics in fields like paleontology and plant phylogenetics have been useful. [18] The spores found in microfossils, also known as cryptospores, are well preserved due to the fixed material they are in as well as how abundant and widespread they were during their respective ...
Sporogenesis is the production of spores in biology.The term is also used to refer to the process of reproduction via spores. Reproductive spores were found to be formed in eukaryotic organisms, such as plants, algae and fungi, during their normal reproductive life cycle.
Seed plants, which first appeared in the fossil record towards the end of the Paleozoic era, reproduce using desiccation-resistant capsules called seeds. Starting from a plant which disperses by spores, highly complex changes are needed to produce seeds. The sporophyte has two kinds of spore-forming organs or sporangia.
A multicellular, glandular hair that usually produces a mucilaginous substance and is located on sepal s, stipules, or petioles, or on nearby parts of stem s; commonly found on plants in the order Gentianales. columella In flowering plants, the central axis of the cone or fruit, e.g. in Callitris. column 1.
Cryptospores are microscopic fossilized spores produced by embryophytes (land plants). They first appear in the fossil record during the middle of the Ordovician period, as the oldest fossil evidence for the colonization of land by plants. A similar (though broader) category is miospores, a term generally used for spores smaller than 200 μm.
Categorized based on developmental sequence, eusporangia and leptosporangia are differentiated in the vascular plants. In a leptosporangium, found only in leptosporangiate ferns, development involves a single initial cell that becomes the stalk, wall, and spores within the sporangium. There are around 64 spores in a leptosporangium.
In flowering plants, the gametophytes are very reduced in size, and are represented by the germinated pollen and the embryo sac. The sporophyte produces spores (hence the name) by meiosis, a process also known as "reduction division" that reduces the number of chromosomes in each spore mother cell by half. The resulting meiospores develop into ...
Most spores germinate by first producing a germ-rhizoid or holdfast followed by a germ tube emerging from the opposite end. The germ tube develops into the hypha, protonema or thallus of the gametophyte. In seedless vascular plants such as ferns and lycopodiophyta, the term "sporeling" refers to the young sporophyte growing on