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By comparison "lycopod" or lycophyte (club moss) means wolf-plant. The term "fern ally" included under Pteridophyta generally refers to vascular spore-bearing plants that are not ferns, including lycopods, horsetails, whisk ferns and water ferns (Marsileaceae, Salviniaceae and Ceratopteris). This is not a natural grouping but rather a ...
The fertile leaves appear first; their green color slowly becomes brown as the season progresses and the spores are dropped. The spore-bearing stems persist after the sterile fronds are killed by frost, until the next season. The spores must develop within a few weeks or fail. The Osmundastrum cinnamomeum fern forms huge clonal colonies in ...
A 2008 review by Gensel notes that recently discovered fossil spores suggest that tracheophytes were present earlier than previously thought; perhaps earlier than supposed stem group members. Spore diversity suggests that there were many plant groups, of which no other remains are known.
Spores form part of the life cycles of many plants, algae, fungi and protozoa. [2] They were thought to have appeared as early as the mid-late Ordovician period as an adaptation of early land plants. [3] Bacterial spores are not part of a sexual cycle, but are resistant structures used for survival under unfavourable conditions. [4]
Consistent with this view, compared to other living land plants, all three lineages lack vascular tissue containing lignin and branched sporophytes bearing multiple sporangia. The prominence of the gametophyte in the life cycle is also a shared feature of the three bryophyte lineages (extant vascular plants are all sporophyte dominant).
The plants have intercalary meristems in each segment of the stem and rhizome that grow as the plant gets taller. This contrasts with most seed plants, which grow from an apical meristem - i.e. new growth comes only from growing tips (and widening of stems). Horsetails bear cones (technically strobili, sing. strobilus) at the tips of some stems.
Fruiting bodies have a short stalk from which arises a spore-bearing structure (the receptaculum) of 5–8 arched arms. These arms, initially joined at the top, disconnect and curve irregularly to expose the inner surface of each arm, which is covered with green spore-containing gleba. Spores are 3–4 × 1–1.5 μm. [12] Aporophallus Möller ...
At one time, the cryptogams were formally recognised as a group within the plant kingdom. In his system for classification of all known plants and animals, Carl Linnaeus (1707–1778) divided the plant kingdom into 24 classes, [1] one of which was the "Cryptogamia". This included all plants with concealed reproductive organs.