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.
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 antheridiaPsilotum gametophyte tissues all haploidarchegonium
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 gametophyte1N antheridium2N rhizome2N rhizoid1N rhizoid
14 CooksoniaRhyniaEarliest Land Plantsfrom theEarly Devonian