- Gymnosperms are non-flowering, seed-bearing plants, which act as a connecting link between Pteridophytes and Angiosperms.
- Sequoia is the tallest and the oldest species, whereas Zamia is the smallest that ranges from 20-25cm.
- Taproots of gymnosperms do not possess root hairs and hence their attachment with fungus (Mycorrhizae) → Eg: pinus (or) Algae (coralloid roots) → Eg: Cycas for N2 fixation process
- The stems are branched (Cedrus, Pinus) (or) unbranched (Cycas)
- Gymnosperms are heterosporous which produce microspores and megaspores that are haploid, which are borne on sporophylls.
- These two types of sprophylls aggregate to form “cones” also called as “strobili”
- Microsporangia is male strobili and the cones possessing megasporophylls with ovules (or) megasporangia are called macrosporangia (or) female strobili.
- The male or female cones may be present on the same tree (Pinus) or on different trees (Cycas).
- In gymnosperms, the female gametophyte does not have an independent existence, unlike bryophytes and Pteridophytes.
- Monoxylic wood and Pyconoxylic wood are its two types of wood.
- Due to persistent cambium, monoxylic wood is formed in one ring, when cambial activity is short lived and posses softwood and are commercially useless Eg. Cycas
- Cambial activity is long lived and therefore the wood is formed in more than one ring which makes the wood harder and commercially useful. Eg. Pinus.
- Gymnosperms are mainly classified into Cycas and Pinus.
- Gymnosperms are mainly classified into three classes (i) Cycadopsida [Eg. Cycas] (ii) Coniferopsida [Eg. Pinus] and (iii) Gnetopsida [Eg. Gnetum]
- Cycas is a palm-like plant, which is a living fossil as it possesses a number of characters of extinct cycads and Pteridophytes.
- Leaves of Cycas are of 2 types – (i) large green foliage and (ii) small brownish scale leaves.
- It possesses coralloid roots that have an association with blue-green algae such as Nostoc and Anabaena.
- Cycasplantss are dioecious i.e. unisexual that reproduces by vegetative propagation and sexual reproduction.
- Pinus is a coniferous gymnosperm that resembles a christmas tree, that has long and dwarf stem branches and possesses a horizontally spreading tap root system with a fungal association.
- Pinus reproduces only by spores and they are monoecious i.e. bisexual and pollination is by air (i.e. anemophilous) and it is direct.
Part-1: View this video for the topic from 0:11 to 9:50
Part-2: View this video for the topic from 0:14 to 13:13
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