Book contents
- Frontmatter
- Contents
- Preface to the first edition
- Preface to the second edition
- 1 General features of the plant kingdom
- 2 The subkingdom Algae: Part 1
- 3 The subkingdom Algae: Part 2
- 4 The subkingdom Algae: Part 3
- 5 The subkingdom Embryophyta: division Bryophyta (mosses and liverworts)
- 6 The subkingdom Embryophyta (cont.): division Tracheophyta, Part 1
- 7 The subkingdom Embryophyta (cont.): division Tracheophyta, Part 2
- 8 The subkingdom Embryophyta (cont.): division Tracheophyta, Part 3
- 9 The subkingdom Embryophyta (cont.): division Tracheophyta, Part 4
- Glossary
- Suggestions for further reading
- Index
9 - The subkingdom Embryophyta (cont.): division Tracheophyta, Part 4
Published online by Cambridge University Press: 05 June 2012
- Frontmatter
- Contents
- Preface to the first edition
- Preface to the second edition
- 1 General features of the plant kingdom
- 2 The subkingdom Algae: Part 1
- 3 The subkingdom Algae: Part 2
- 4 The subkingdom Algae: Part 3
- 5 The subkingdom Embryophyta: division Bryophyta (mosses and liverworts)
- 6 The subkingdom Embryophyta (cont.): division Tracheophyta, Part 1
- 7 The subkingdom Embryophyta (cont.): division Tracheophyta, Part 2
- 8 The subkingdom Embryophyta (cont.): division Tracheophyta, Part 3
- 9 The subkingdom Embryophyta (cont.): division Tracheophyta, Part 4
- Glossary
- Suggestions for further reading
- Index
Summary
SPERMATOPHYTINA (cont.): ANGIOSPERMS (flowering plants)
The angiosperms are the most abundant and widely distributed of the seed-bearing tracheophytes. They are of outstanding economic importance, being the source of many durable hardwoods, most of our vegetable foodstuffs, and about one-quarter (in monetary value) of commercially marketed drugs. They number some 250000 species and show remarkable diversity in growth form, morphology and physiology.
The general features of the angiosperms can be summarized as follows:
Sporophyte herbaceous or arborescent; branching usually axillary. Leaves various, but regarded as megaphyllous in origin. Secondary vascular tissue commonly present. Vascular system usually consisting of vessels and tracheids, and sieve tubes with distinctive companion cells. Heterospory as in the gymnosperms, but the ovules borne within a characteristic structure (carpel), usually closed, the pollen germinating on a specialized region of the exterior (stigma). Female gametophyte always an embryo sac, lacking archegonia. Male cells (sperms) lacking specialized means of locomotion, released into the embryo sac from the filamentous male gametophyte (siphonogamy). Fertilization characteristically double, yielding in each embryo sac a zygote and a mostly triploid endosperm nucleus. Embryogeny endoscopic. Various forms of asexual reproduction not uncommon.
Magnoliopsida and Liliopsida
The angiosperms fall into two major classes, the Magnoliopsida (dicotyledons) and the Liliopsida (monocotyledons), in which the embryos are commonly furnished with two or only one cotyledon respectively. These groups also differ in many other features, with distinct trends in leaf venation and form, and flower symmetry.
- Type
- Chapter
- Information
- Green PlantsTheir Origin and Diversity, pp. 269 - 316Publisher: Cambridge University PressPrint publication year: 2000