1121 - November 21, 2011 Lecture 5 1. gymnosperms a)...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
November 21, 2011 Lecture 5 1. gymnosperms a) non-flowering plants without ovaries or fruits that enclose the seeds b) seeds are held on fleshy or woody leaf-like structures = megasporophylls, often arranged in cones c) includes ~85 genera 2. angiosperms a) flowering plants with true fruits that enclose the sees b) include over 250,000 species 3. coniferous forests, dominated by gymnosperms, cover nearly 25% of the land surface of the earth 4. review: evolutionary trend towards greater sporophytic dominance 5. characteristics of gymnosperms a) heterosporous; microspores and megaspores are produced in different strobili on the sporophyte b) megaspores produced on megasporophylls (arranged in megastrobili) megaspore → megagametophyte → archegonia → eggs c) microspores are produced on microsporophylls (arranged in microstrobili) microspore → microgametophyte (pollen grain) → sperm d) no antheridium e) the sporophyte is usually woody f) the xylen of gymnosperms is composed of only tracheids g) megagametophytes develop within ovules h) ovules develop into seeds (embryos and their maternal food are contained within the seed coat). Therefore, gymnosperms produce seeds! 6. foreshadowing. ....evulotionary trends we will see in the angiosperms a) loss of both antheridia and archegonia b) increaed protection of the egg c) production of highly attractive reproductive structures that attract animals that facilitate
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 12/07/2011 for the course EEMB 3 taught by Professor Carlson during the Fall '08 term at UCSB.

Page1 / 3

1121 - November 21, 2011 Lecture 5 1. gymnosperms a)...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online