Carolus Linnaeus - late 18thC Species Plantarum 1753 Systems Naturae (24) major categories of plants (Divisions) - (23) vascular (Phanerogams); - (1) non-vascular & vascular (Cryptogams)

K: Plantae - Ordovician - Non-vascular - Silurian - Vascular

Continental Positions During Early Plant Evolution

Vascular Plants - The Tracheophytes 1. Have specialized cell type for conducting water - tracheids (early xylem tissue). Also has specialized cell type for conducting sugar - seive cells (phloem tissue). 2. Lignin in xylem for rigid structural support. 3. A branching, independent sporophyte.

Vascular Plants - The Tracheophytes

Vascular Plants - The Tracheophytes (300 mya) Non-seed Tracheophytes - haloid & diploid generations totally independent - spores most prominent resting state

Rhyniophyta - the earliest Tracheophytes (extinct by Devonian Period 400 mya) 1. Simple vascular system (xylem & phloem) in stem. 2. “Leaves” flattened scales - no vascular tissue. 3. No roots - but rhizomes. 4. Dichotomous stem branching. 5. Aerial branches and sporangia at branch tips. 6. Spores were in groups of four (?) tetrads - indicate meiosis plant body - a sporophyte (2n) spores - (n) ---> gameophyte (n)--> sexual reproduction--> sporophyte (2n) (fossil)

Lignier’s Hypothesis (1903) How Roots Evolved from Stems ancestoral form --->

Evolution of Leaves Leaf - a flattened photosynthetic structure emerging from the stem and possessing true vascular tissue. Probably evolved from sterile sporangia.

Evolution of Leaves Leaf - a flattened photosynthetic structure emerging from the stem and possessing true vascular tissue. Complex leaves arose as photosynthetic tissue developed between complex branching patterns

Homospory The Most Primitive Spore Process one type of spore; one type of gametophyte

Heterospory The Most Advanced Spore Process two types of spores; two types of gametophytes heterospory probably evloved several times

K: Plantae Div: Lycophyta G: Lycopodium “ground pines” 1. Leaves small and sessile; no ligule at base. 2. Stems with aerial branches and rhizomes; dichotomous branching. 3. Branch roots originate deep within main root. 4. Mainly perennial. 5. Low growing in temperate forest or epiphyte in Tropical forest. 6. Homosporous.

K: Plantae Div: Lycophyta G: Lycopodium “ground pines” Plectostele - dissected xylem with phloem branches in between. –Xylem - all tracheids. –Phloem - all seive cells Epidermis - contains stomata.

K: Plantae Div: Lycophyta G: Lycopodium “ground pines” Plectostele - Always a layer of parenchyma cells between xylem and phloem.

K: Plantae Div: Lycophyta G: Lycopodium “ground pines” Plectostele - dissected xylem with phloem branches in between. –Xylem - all tracheids. –Phloem - all seive cells –mucilaginous canal Epidermis - contains stomata. Exarch Stele -

K: Plantae Div: Lycophyta G: Lycopodium “ground pines” A. Exarch Stele - B. Mesarch Stele C. Endarch Stele

K: Plantae Div: Lycophyta G: Lycopodium “ground pines” Sexual Reproduction: sporophyte (2n) ---- meiosis ----> > spores (n) --> gametophyte (n) --> antheridia (n) & archegonia (n) (homospores) antheridium ----> sperms (n) -- fertilization --> zygote (2n) --> sporophyte (2n) Archegonium ----> egg (n)

K: Plantae Div: Lycophyta G: Lycopodium “ground pines”

K: Plantae Div: Lycophyta G: Lycopodium “ground pines” Sexual Reproduction: sporophyte (2n) ---- meiosis ----> > spores (n) --> gametophyte (n) --> antheridia (n) & archegonia (n) antheridium ----> sperms (n) -- fertilization --> zygote (2n) --> sporophyte (2n) Archegonium ----> egg (n)

K: Plantae Div: Lycophyta G: Lycopodium “ground pines” MALE GAMETOPHYTE: Antheridia (n) on crown. Embedded (like Anthoceratophyta) Biflagellated sperms (n) FEMALE GAMETOPHYTE looks much the same.

K: Plantae Div: Lycophyta G: Lycopodium “ground pines”

K: Plantae Div: Lycophyta G: Lycopodium “ground pines” strobilus (2n) - stem with short internodes and fertile appendages sporophyll (2n) sporangium (2n) spores (n) l

K: Plantae Div: Lycophyta G: Lycopodium “ground pines” sporophyll & sporangium adaxial view

K: Plantae Div: Lycophyta G: Lycopodium “ground pines”

K: Plantae Div: Lycophyta G: Lycopodium “ground pines” gemmae or bulbils (2n) (asexual reproduction) axial sporophylls g

K: Plantae Div: Lycophyta G: Selaginella “ground pines” Mainly in tropical areas g

K: Plantae Div: Lycophyta G: Selaginella “ground pines” 1. Herbaceous: perennial. 2. Ligulate* leaves; microphyllous; spirally or alternately arranged. 3. Abundant branching. 4. Some vessels* in xylem. g

K: Plantae Div: Lycophyta G: Selaginella “ground pines” 1. Herbaceous: perennial. 2. Ligulate*leaves; microphyllous; spirally or alternately arranged. 3. Abundant branching. 4. Some vessels* in xylem. 5. Strobilus composed of sporophylls each bearing a single sporangium on the adaxial surface. 6. Heterosporous* reproduction. g

K: Plantae Div: Lycophyta G: Selaginella “ground pines” 6. Heterosporous* reproduction. Strobilus (2n) --> microsporophylls (2n) --> microsporangium (2n) --> megasporophylls (2n) --> megasporangium (2n) --> meiosis microsporangium (2n) --> microsporocytes (2n) > microspores (n) megasporangium (2n) --> (4) megasporocytes (2n) > (4) megaspores (n) g

K: Plantae Div: Lycophyta G: Selaginella “ground pines” meiosis microsporangium (2n) --> microsporocytes (2n) > microspores (n) megasporangium (2n) --> (4) megasporocytes (2n) > (4) megaspores (n) --> microspores (n) --> male gametophytes (n), antheridium --> sperms (n) --> (4) megaspores (n) --> female gametophytes (n), archegonium --> egg (n) dioecious triradiate walls --> g

K: Plantae Div: Lycophyta G: Selaginella “ground pines” fertilization - -> zygote (2n) --> adult sporophyte (2n)

K: Plantae Div: Lycophyta G: Selaginella “ground pines” fertilization - -> zygote (2n) --> adult sporophyte (2n)

K: Plantae Div: Lycophyta G: Selaginella “ground pines” g

K: Plantae Div: Lycophyta G: Isoetes “quillworts” 1. Quill-like leaves spirally attached to a corm; microphyllus and ligulate. Corm - thickened underground stem. Nodes very close together. Lacunae --->

K: Plantae Div: Lycophyta G: Isoetes “quillworts” 1. Quill-like leaves spirally attached to a corm; microphyllus and ligulate. Corm - thickened underground stem. Nodes very close together. 2. Each leaf has 4 lacunae; stomata in epidermis. * 3. Some seive cells lack nucleus at maturity - plasmodesmata with adjacent cells. 4. Stem and root protostelic. 5. Xylem consists of large numbers of parenchyma cells with few tracheids. * 6. Delicate roots grow from base of corm (rhizophores); stele bound by well defined endodermis*; have root caps.

K: Plantae Div: Lycophyta G: Isoetes “quillworts” 7. Heterosporous. 8. Every leaf of Isoetes is potential a sporophyll; per season - sterile leaves 1st; then megasporophylls; then microsporophylls. --> 1 million microspores; > 300 megaspores.

K: Plantae Div: Lycophyta G: Isoetes “quillworts” Sporangium massive > 7mm. Velum - covering over sporangium. Trabecula - strands of sterile tissue extending from the sporangial wall. Tapetum - innermost layer of the sporangial wall. Indistinguishable.

K: Plantae Div: Lycophyta G: Isoetes “quillworts” meiosis (all spores set free) microsporangium (2n) > microspores (n) --> male gametophyte (n) megasporangium (2n) > megaspores (n) --> female gametophyte (n) male gametophyte (n) --> antheridium (4 sperms) multiflatelated female gametophyte (n) --> archegonium (1 egg) *further reduction of gametophyte!* colorless, saprophytic

K: Plantae Div: Lycophyta G: Isoetes “quillworts” male gametophyte (n) --> antheridium (4 sperms) female gametophyte (n) --> archegonium (1 egg) *further reduction of gametophyte!* colorless, saprophytic no suspensor 1 embryo develops from each gametophyte

K: Plantae Div: Lycophyta G: Isoetes “quillworts” No suspensor; delayed development of the stem.