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Spore Shedding Vascular Plants

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Presentation on theme: "Spore Shedding Vascular Plants"— Presentation transcript:

1 Spore Shedding Vascular Plants
Psilotum Lycopodium Equisetum

2 Psilotum nudum (whisk fern)

3 Psilotum nudum (whisk fern)

4 Psilotum has a stem doing virtually all the photosynthesis, with dichotomous branching, enations without vascular tissue, and yellow synangia in the axils of the enations. Below ground, the stem is not photosynthetic but the epidermis forms rhizoids for anchorage. The plant thus lacks roots and leaves with underground stem (rhizome) doing the anchorage functions.

5 Psilotum stem cross section
radial exarch triarch actinostele cutin guard cells epidermis PSN cortex lignified cortex respiring cortex phloem metaxylem protoxylem

6 Protosteles: haplosteles actinostele plectostele Siphonosteles:
cortex phloem xylem Siphonosteles: siphonostele solenostele dictyostele cortex phloem xylem pith leaf gap leaf trace eustele atactostele dicot stem monocot stem

7 Psilotum stem specimen more than triarch

8 Psilotum rhizomes with rhizoids

9 Psilotum rhizome cross-section

10 Psilotum stem demonstrates dichotomous branching, enations (no vascular tissue) and two of the three sporangia in a single synangium

11 Psilotum sporangium (a three-parted synangium)
This specimen has shed its spores into the wind and so the sterile jackets are empty. At the bottom of the view is a partial stem cross-section showing: epidermis, cortex and a portion of the vascular cylinder.

12 Psilotum gametophyte tissues all haploid
antheridia Psilotum gametophyte tissues all haploid archegonium

13 Psilotum gametophyte (SE to NW) and sporophyte (Y-shape)
The photo is flipped and cropped. Some versions of Powerpoint may fail to retain this making the labels erroneous! 1N gametophyte 1N antheridium 2N rhizome 2N rhizoid 1N rhizoid

14 Cooksonia Rhynia Earliest Land Plants from the Early Devonian

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