Seedless Vascular Plants

Protostele

The simplest type of stele, consisting of a solid column of vascular tissue.

Siphonostele

A type of stele; hollow cylinder of vascular tissue surrounding a pith; no leaf gaps

Eustele

advanced stele; vascular bundles in ring around central pith

Microphylls

leaves with a single vein, no leaf gap; began as enations, assoc. with protostele

Enations

small outgrowths; evolved into leaves

Megaphylls

leaves with a highly branched vascular system, leaf gap; derived from fusion of branches, assoc w/ siphonstele or eustele

Homosporous

producing one type of spore that develops into a bisexual plant

Heterosporous

producing two types of spores (megaspores and microspores), unisexual offspring

Lycopodium (Lycopodiophyta) Life Cycle

homosporous (bisexual), contains strobili and sporophylls, sporophyte independent of gametophyte, water needed for fertilization (!sporophyte dominant generation!)

Strobilus

a cluster of sporangia on stalk

Sporophyll

a leaf that bears sporangia

Selaginella (Lycopodiophyta) Life Cycle

heterosporous (unisexual), strobili w/ sporophylls, sporophyte independent of male/female gametophytes, water needed for fertilization (!sporophyte dominant generation!)

Equisetum (Monilophyta, Order Psilotales) Life Cycle

homosporous (bisexual), strobili w/ sporangiophores, sporophyte independent of gametophyte, water needed for fertilization (!sporophyte dominant generation!)

Circinate Vernation

unrolling of fern fronds

Sori

clusters of sporangia on underside of fern megaphylls (fronds)

Indusium

leaf tissue covering fern sorus

Fern (Monilophyta, Order Polypodiopsida) Life Cycle

homosporous (bisexual), sporangium in sori under megaphylls, sporophyte independent of heart-shaped gametophyte, water needed for fertilization (!sporophyte dominant generation!)