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Cycadophyta, Ginkgophyta

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Presentation on theme: "Cycadophyta, Ginkgophyta"— Presentation transcript:

1 Cycadophyta, Ginkgophyta
Lab 12 Cycadophyta, Ginkgophyta

2 Seed plants General features of the vascular plants
Common name: Seed plants Synonyms: Spermatophyta Sporophyte growth habit: Stems, leaves, roots Gametophyte growth habit: Endosporic thalli

3 Seed plants Stele: Eustele
Undulipodia (“flagella”): Whiplash (100 to 1000+) or none Sexual reproduction: Heterosporous Included Phyla: Cycadophyta, Ginkgophyta, Coniferophyta, Gnetophyta, Anthophyta Recognized by: Seeds, wood, eustele

4 Cycadophyta General features of the seed plants Common name: Cycads
Synonyms: None Sporophytes: Dioecious; trees, shrubs with compound leaves and often only a single trunk. Strobili: Simple pollen cone; simple seed cone

5 Cycadophyta Undulipodia (“flagella”): Whiplash, more than 100
Representative genera: Cycas, Zamia Recognized by: Thick compound leaves, cones

6 P Various cycads Cycadophyta
Left: Cycas revoluta behind Bldg. 1, growing at the base of a Beaucarnea. Right: Pollen cone on a Zamia. Cycadophyta

7 D Microsporangiate strobili
Top left: Pollen cone, genus unknown. Right: Pollen cone, Zamia. Lower left: underside of microsporophyll, showing microsporangia. Cycadophyta

8 D Megasporangiate strobili
Left: Seed cone, genus unknown. Right: Megasporophyll from same genus, showing two ovules. Cycadophyta

9 A Cycad seeds Upper right: Zamia. Lower left: Cycas. Cycadophyta

10 A Zamia ovule Cycadophyta
Upper: Typical of the slides in the lab boxes, with substantial shrinkage. Lower: Slide from the demo box. Click on either to bring up the respective Flash animations. Cycadophyta

11 A Cycas microsporophyll
Below: Underside of sporophyll showing microsporangia. Above: Section of roughly the same structure. Close-up on next slide. Cycadophyta

12 A Cycas microsporophyll
Note the body of the sporophyll and the microsporangia, each with sterile jacket and pollen grains. Cycadophyta

13 Ginkgophyta General features of the seed plants
Common name: Ginkgo, Maidenhair tree Synonyms: None Sporophytes: Dioecious; tree Strobili: Simple pollen cone; no seed cone (ovules paired on the end of a slender branch)

14 Ginkgophyta Undulipodia (“flagella”): Whiplash, more than 1000
Representative genera: The single species Ginkgo biloba Recognized by: Fan-shaped leaves, seeds not in cones, smelly sarcotesta

15 P Ginkgo Note the bilobed leaves, characteristic of long shoots. Ginkgophyta

16 D Ginkgo stem Ginkgophyta
Identify pith, secondary xylem, vascular cambium, secondary phloem, cortex, resin ducts, periderm. Ginkgophyta

17 D Ginkgo pollen cone Ginkgophyta
Left: Preserved pollen cone in normal hanging orientation. Right: Close-up of a microsporophyll, turned “anatomically” upright. Note the two microsporangia. Ginkgophyta

18 A Ginkgo “male” (pollen) strobilus
Each view shows a microsporophyll sliced through one of the two microsporangia. Ginkgophyta

19 P Ginkgo seeds Ginkgophyta
Top: inside of the sclerotesta, showing the endotesta. Bottom: On the right, the sclerotesta is broken away to show the female gametophyte enclosed in the nucellus, and a torn portion of the endotesta. Ginkgophyta

20 P Ginkgo seeds Ginkgophyta
The female gametophyte is covered on the left (the end away from the micropyle) by the fused endotesta and nucellus. On the right, the outer torn layer is the endotesta and the inner intact layer is the nucellus. Ginkgophyta

21 P Ginkgo seeds Ginkgophyta
The thin white membranous layer is the cell wall of the megaspore. Inside it is the greenish female gametophyte and outside is the brown nucellus. Ginkgophyta

22 P Ginkgo seeds Ginkgophyta
The embryonic sporophyte sits in place in the sectioned female gametophyte, which is still enclosed in the nucellus. Notice the radicle, cotyledons, and hypocotyl. Ginkgophyta

23 P Ginkgo seeds Ginkgophyta
Notice the epicotyl between the two spread cotyledons. Ginkgophyta

24 P Ginkgo seeds Ginkgophyta
With one cotyledon removed, the epicotyl is easily seen. Ginkgophyta

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