Heterospory means the formation of two distinctly different spores. The smaller one, designated as microspore later on gives rise to the male gametophyte and the larger one called megaspore gives rise to female gametophyte. Heterospory commonly occurs in all gymnosperms and certain pteridophytes such as Selaginella.

What causes heterospory?

Origin of Heterospory

Heterospory evolved due to natural selection that favoured an increase in propagule size compared with the smaller spores of homosporous plants. ... This may first have led to an increase in spore size and ultimately resulted in the species producing larger megaspores as well as smaller microspores.

What is heterospory and where it is found?

Hint: Heterospory is found in some members of cryptogams and all members of seed producing plants. Heterospory is the production of spores of two different sizes and sexes by the sporophytes of land plants. Heterospory is evolved from homospory as a part of the process of evolution.

What is heterospory give an example?

Heterospory is the phenomenon of formation of two types of spores, i.e., smaller microspore and larger megaspore. ... Examples of heterospory are Selaginella, Salvinia and Marsilea, etc.

What is the heterosporous life cycle?

A heterosporous life history occurs in some pteridophytes and in all seed plants. It is characterized by morphologically dissimilar spores produced from two types of sporangia: microspores, or male spores, and megaspores (macrospores), or female spores.

What is HETEROSPORY? What does HETEROSPORY mean? HETEROSPORY meaning, definition & explanation

34 related questions found

What is mean by H * * * * * * * * * * and Heterosporous Pteridophytes give two examples?

HOMOSPOROUS PETRIDOPHYTES : The plants which produce only one kind of spores called homosporous pteridophytes. Ex: psilotum. ⭐.HETEROSPOROUS PTERIDOPHYTES : The plants which produce two kinds of spore on the same plant are these type. Ex : salvinia.

What is the difference between H * * * * * * * * * * and Heterosporous?

Plants that are homosporous produce spores of the same size and also type. Heterosporous plants produce spores of two different sizes which are the larger spore called the megaspore, functioning as a female spore and the smaller spore known as the microspore that functions as a male spore.

What do you mean by Diplohaplontic life cycle?

(of an alga or other lower plant) having a life cycle in which full-grown haploid and diploid forms alternate. ... 'Sporic life cycles are sometimes called diplohaplontic, indicating that both diploid and haploid free-living stage occur. '

Is pteris Homosporous or heterosporous?

All bryophytes are homosporous and all gymnosperms are heterosporous. This condition is advanced as sexual dimorphism result in cross fertilization. Primitive or earlier Pteridophyta are homosporous later pteriodophytes are heterosporouse. g., Dryopteris, Pteris homosporous Selaginella, Salvinia-heterosporous.

What is meant by heterosporous Fern give two examples?

Selaginella and Salvinia are two examples of heterosporous pteridophytes. These pteridophytes consist of two types of spores, large spores that germinate to produce female gametophyte and small spores germinate to produce male gametes.

What is sporangium and Sporangiophore?

The sporangium forms on the sporangiophore and contains haploid nuclei and cytoplasm. Spores are formed in the sporangiophore by encasing each haploid nucleus and cytoplasm in a tough outer membrane. During asexual reproduction, these spores are dispersed via wind and germinate into haploid hyphae.

Which is the first step of seed habit?

Psilotum is a pteridophyte which is known as primitive pteridophyte. It is an example of a living fossil fern. In pteridophytes, the development of the zygote into a young embryo takes place within the female gametophytes. This is the first step towards the evolution of seed habit that is seen in higher plants.

Are all seed plants Heterosporous?

Whereas lower vascular plants, such as club mosses and ferns, are mostly homosporous (produce only one type of spore), all seed plants, or spermatophytes, are heterosporous. They form two types of spores: megaspores (female) and microspores (male).

Why seeds are not formed in Pteridophytes?

Even then the seeds are not formed in Selaginella because:

1. Megasporangium is not surrounded by integument. 2. The retention of megaspore permanently inside the megasporangium has not been well established.

Do bryophytes produce seeds?

Bryophytes produce spores, rather than seeds, and have no flowers. ... They also have no flowers and produce spores.

What is precursor of seed habit?

The development of the zygotes into young embryos take place within the female gametophytes. This event is a precursor to the seed habit considered an important step in evolution.

Which fern is Woody?

Unlike flowering plants, tree ferns do not form new woody tissue in their trunk as they grow. Rather, the trunk is supported by a fibrous mass of roots that expands as the tree fern grows.

Is heterospory found in bryophytes?

While all bryophytes are homosporous, several lineages of vascular seedless plants as well as the entire seed plant lineage have evolved heterospory (Bateman and DiMichele, 1994).

Do bryophytes show heterospory?

Since Bryophytes are homosporous, they do not show heterospory.

What is the difference between Diplohaplontic and Haplodiplontic?

As adjectives the difference between diplohaplontic and haplodiplontic. is that diplohaplontic is (biology) describing a life cycle that has alternating haploid and diploid phases while haplodiplontic is (biology|of a life cycle) having multicellular diploid and haploid stages.

What is Heteromorphic alternation of generation?

Heteromorphic alternation of generation occurs in organisms in which the haploid gametophyte phase and diploid sporophyte phase are different in form.

Which type of life cycle is shown by kelps Ectocarpus and Polysiphonia?

Answer: Haplo diplontic type of life cycle is exhibited by Ectocarpus, Polysiphonia and Kelps.

Is Cycas a heterosporous?

Cycas is a gymnosperm plant that belongs to the Cycadaceae family. ... They are heterosporous plants, which means they produce two different types of spores.

What is Homospory?

: the production by various plants (such as the club mosses and horsetails) of asexual spores of only one kind.

What is Homosporous?

homosporous. / (hɒˈmɒspərəs, ˌhəʊməʊˈspɔːrəs) / adjective. (of most ferns and some other spore-bearing plants) producing spores of one kind only, which develop into hermaphrodite gametophytesCompare heterosporous.