Sorus | plant anatomy | ddttrh.info
With a 10x hand lens, you'll be able to see that the sori are composed of numerous, small, Most ferns produce 64 spores in each sporangium. as venation, origin of the sorus, indusium, development of the sporangium, scales . number in relation to the world flora) had either trilete or monolete spores. Third specimens with a copious quantity of sporangia and spores that came from. Sporangia are the spore producing structures of plants, fungi and alga. Some species contain clusters of Sporangia, such as the clumps of.
Ferns are a very ancient family of plants: They are older than land animals and far older than the dinosaurs.
- What is the relationship between sori, sporangia and spores?
They were thriving on Earth for two hundred million years before the flowering plants evolved. As we know them now, most ferns are leafy plants that grow in moist areas under forest canopy. They are "vascular plants" with well-developed internal vein structures that promote the flow of water and nutrients. Unlike the other vascular plants, the flowering plants and conifers, where the adult plant grows immediately from the seed, ferns reproduce from spores and an intermediate plant stage called a gametophyte.
What makes them different from other vascular plants? There are two answers to this. The first is that ferns are relatively delicate plants that only grow in areas where there are suitably moist conditions.
They favour sheltered areas under the forest canopy, along creeks and streams and other sources of permanent moisture. They cannot grow readily in hot dry areas like flowering plants and conifers.
The second explanation ties in with the first: It all has to do with moisture. Not just the moisture that allows the plant to live where it does, but the moisture that allows it to reproduce there. How do they reproduce? As flowering plants are so common, we are all familiar with how they reproduce.
Flowering plants and conifers reproduce when pollen from a male flower - carried by wind, insect or other vector - fertilises the female flower. Many flowering plants, of course, include both male and female parts in the same flower. The male pollen cell carries half the genetic material of the adult plant and fuses its genetic material with that of the female cell, which carries the other half.
The complete, fertilised cell grows into the seed, which, when ripe and when it finds itself in suitable soil and moisture, is capable of producing a complete adult plant.
Higher plants have a very robust propagation system: The seeds themselves are often very durable, able to wait for long periods in adverse conditions before they grow.
So the higher vascular plants have evolved to occupy nearly every niche on the land surface of the earth.
Sorus - Wikipedia
Ferns do it differently. They have a more complicated method that depends on there being liquid water for the process to complete. As a result, they can only reproduce where there is sufficient moisture: So, how do they do it? Parts of the fern - and some names for them The leafy branch of the fern is usually called a frond. The small leaflets that make up the whole frond are called pinnae.
If you look underneath a fern frond, you will often see small clumps, spots or patches that look like they are stuck onto the under surface of the pinnae. These patches are where you find the spores. The spores grow inside casings called sporangia. The sporangia may clump together into what are called sori singular: Photo A below shows sporangia clumped into sori on a Kangaroo Fern frond.
Sometimes these sori follow the fern leaf veins, sometimes they are set into indentations in the underside of the pinna. Not every frond has spores under it: Take a look more closely at the spore structures under the pinnae of a fertile frond, using a hand lens.
In some cases, you will see that each is composed of myriads of smaller structures. These are the sporangia - the spore casings that hold the spores. Some ferns protect their sporangia with thin semi-transparent membranes, often globular in shape, called indusia. Leaves that bear sporangia are called sporophylls. If the plant is heterosporous, the sporangia-bearing leaves are distinguished as either microsporophylls or megasporophylls.
In seed plants, sporangia are typically located within strobili or flowers. Cycads form their microsporangia on microsporophylls which are aggregated into strobili. Megasporangia are formed within ovules, which are borne on megasporophylls, which are aggregated into strobili on separate plants all cycads are dioecious. Conifers typically bear their microsporangia on microsporophylls aggregated into papery pollen strobili, and the ovules, are located on modified stem axes forming compound ovuliferous cone scales.
Flowering plants contain microsporangia in the anthers of stamens typically four microsporangia per anther and megasporangia inside ovules inside ovaries. In all seed plants, spores are produced by meiosis and develop into gametophytes while still inside the sporangium. The microspores become microgametophytes pollen. The megaspores become megagametophytes embryo sacs. Eusporangia and leptosporangia[ edit ] Categorized based on developmental sequence, eusporangia and leptosporangia are differentiated in the vascular plants.
In a leptosporangium, found only in 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 a eusporangium, characteristic of all other vascular plants and some primitive ferns, the initials are in a layer i.
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A eusporangium is larger hence contain more sporesand its wall is multi-layered. Although the wall may be stretched and damaged, resulting in only one cell-layer remaining. Synangium[ edit ] A cluster of sporangia that have become fused in development is called a synangium. This structure is most prominent in Psilotum and Marattiaceae such as ChristenseniaDanaea and Marattia.