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Spore Shedding Vascular Plants Psilotum Lycopodium Equisetum.

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Presentation on theme: "Spore Shedding Vascular Plants Psilotum Lycopodium Equisetum."— 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 epidermis cutinguard cells PSN cortex lignified cortex respiring cortex phloem metaxylem protoxylem radialexarchtriarchactinostele

6 haplosteles siphonostele eustele solenosteledictyostele atactostele leaf gap leaf trace cortex cortex phloem xylem cortex pith cortex phloem xylem pith dicot stem monocot stem Protosteles: actinosteleplectostele Siphonosteles:

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 archegonium antheridia

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

14 RhyniaCooksonia Earliest Land Plants from the Early Devonian

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