Homospory and Heterospory

Homospory and Heterospory - the larger or megaspores...

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Homospory and Heterospory Plants have two further variations on their life cycles. Plants that produce bisexual gametophytes have those gametophytes germinate from isospores ( iso =same) that are about all the same size. This state is referred to as homospory (sometimes referred to as isospory). A generalized homosporous plant life cycle is shown in Figure 5. Homosporous plants produce bisexual gametophytes. Ferns are a classic example of a homosporous plant. Plants that produce separate male and female gametophytes have those gametophytes germinate from (or within in the case of the more advanced plants) spores of different sizes (heterospores; hetero =different). The male gametophyte produces sperm, and is associated with smaller or microspores . The female gametophyte is associated with
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Unformatted text preview: the larger or megaspores . Heterospory is considered by botanists as a significant step toward the development of the seed. A generalized heterosporous life cycle is shown in Figure 6. Bryophytes Bryophytes are small, nonvascular plants that first evolved approximately 500 million years ago. The earliest land plants were most likely bryophytes. Bryophytes lack vascular tissue and have life cycles dominated by the gametophyte phase, as shown in Figure 7. The lack of conducting cells limits the size of the plants, generally keeping them under 5 inches high. Roots are absent in bryophytes, instead there are root-like structures known as rhizoids . Bryophytes include the hornworts, liverworts, and mosses....
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This note was uploaded on 11/29/2011 for the course BIO BSC1010 taught by Professor Gwenhauner during the Fall '10 term at Broward College.

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Homospory and Heterospory - the larger or megaspores...

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