Plant Systematics Exam 2 (3/19)

• Memorize family differences

  • know how to match based on characteristics/definitions

• Learn lecture material

• Review field plants

Fern Lecture

• Fern Allies

  • similar to ferns, both sporophyte and gametophyte life cycles

  • dispersal is haploid, spores not retained in special structures

• Lycopodiaceae

  • 350-400 species, 6 in MS

  • Herbaceous, stems densely leafy, usually dichotomously branched

  • Leaves simple, 1-veined, linear or scale like (microphylls), lacking ligules, often in spirals around the stem

  • Plants homosporous

  • Two examples, Lycopodium clavatum (running club-moss) and Diphasiastrum digitatum (ground pine)

• Selgainellaceae

  • 700 species, 3-4 in MS

  • Leaves simple, 1-veined, often in 2 planes

  • Leaves are cale-like with ligules produced in leaf axils

  • Plants hererosporous

  • 1 example, Lycopodioides apodum (meadow spikemoss)

• Isoetaceae

  • 150 species, ~5 in MS

  • Leaves simple, 1-veined (microphylls), long and “quill”-like or grass-like.

  • Leaves are scale-like with ligules (tongue-like flaps) produced in leaf axils.

  • Plants heterosporous.

  • Our Isoetes louisianensis is classified as endangered. First described in 1973

• Equisetaceae

  • 15 species, 2 in MS

  • Stems hollow, jointed.

  • Leaves scale-like, whorled, connate, forming a sheath around the stem.

  • Sporangia on stalks (sporangiophores) and clustered in a cone (strobilus).

  • Plants are homosporous.

• Fern Allies VS True Ferns

  • True ferns have megaphylls, or fronds, rather than microphylls.

  • True ferns have sporangia on the underside of the leaves
    (fern allies have sporangia only in the axils of leaves).

  • Almost all true ferns have circinate vernation.

• Eusporangiate Ferns:

  • Sessile sporangia

  • Large sporangia

  • Sporangia develop from a group of cells

  • Sporangia have no specialized dehiscence cells

  • Sporangia produce many spores

  • Vernation erect

• Leptosporangiate Ferns:

  • Stalked sporangia

  • Small sporangia

  • Sporangia develop from a single cell

  • Sporangia usually have an annulus

  • Sporangia produce few spores

  • Vernation circinate

• Eusporangiate Ferns (Ophioglossaceae):

  • Fern commonly with only 1 leaf, rarely 2 or more.

  • Sterile leaves joined to fertile leaves by a common petiole.

  • Leaves either entire or pinnately compound.

  • 11 species in Mississippi.

  • 2-4 genera: Ophioglossum, Botrychium (+ Sceptridium, Botrypus).

• Leptosporangiate Ferns (Osmundaceae):

  • Large, thickened rhizomes (underground stems).

  • Upright leaves, coarse in texture, always compound.

  • Petiole has stipule-like wings at the base.

  • Leaves divided into fertile and sterile parts, or separate fertile and sterile leaves in some species.

Gymnosperms

• Cycadales (Cycadaceae & Zamiaceae):

  • Palm-like, slow-growing gymnosperms.

  • Pinnate leaves in a crown arrangement.

  • Dioecious with cone-like structures.

  • Cycadaceae: loose megasporophylls; Zamiaceae: true cones.

• Ginkgo (Ginkgoaceae):

  • Deciduous gymnosperm with fan-shaped leaves.

  • Dioecious, with separate male and female trees.

  • Only surviving species: Ginkgo biloba.

• Cupressaceae

  • Persistent, scale-like or rarely needle-like leaves

  • Cone scales diverse, often T-shaped, sometimes fleshy (junipers/cedars)

  • Monoecious or dioecious (junipers)

• Pinaceae

  • Eventually deciduous, linear or needle-like leaves

  • Cone scales flat

  • Monoecious

Magnoliids

• Stamens:

  • Leaf-derived structures that initially bore flat male sporangia.

  • The laminar portion reduced, leaving only the midvein with specialized sacs for pollen.

• Carpels:

  • Leaf-derived structures with flat surfaces that bore ovules (female sporangium surrounded by integuments).

  • Over time, carpels enclosed the ovules to form a protective “house.”

  • Suture lines show evidence of this fusion.

• Nymphaeaceae – “Water Lilies”

  • Aquatic, often with floating leaves

  • Sepals and petals hard to distinguish, usually numerous (tepals)

  • Numerous stamens, intergrading from tepals

  • Numerous pistils, partially fused into a cheese-wheel structure

• Magnoliaceae

  • Trees and shrubs with encircling stipules

  • Perianth of 6+ parts, spiraled in weak whorls of 3

  • Numerous stamens

  • Numerous pistils

  • Fruit aggregates of follicles or samaras

• Annonaceae

  • Mostly tropical trees and shrubs

  • 2-ranked leaves, no stipules

  • 3 sepals, 6 petals

  • Numerous stamens

  • Numerous pistils

  • Fruit an aggregate of berries, sometimes fused when mature

• Lauraceae

  • Includes “bays,” “cinnamon,” “sassafras,” “avocado”

  • Mostly trees and shrubs

  • Leaves contain ethereal oils

  • Perianth of 6 parts (tepals)

  • 6 stamens, anthers open by valvate dehiscence (“Mickey Mouse”)

  • 1 pistil with 1 ovule/seed

  • Fruit a berry or drupe (e.g., avocado), often surrounded by perianth cup

• Illiciaceae – “Anise,” “Stinkbush”

  • Shrubs

  • Numerous tepals

  • Numerous stamens

  • Numerous pistils, arranged in a whorl like a cheese-wheel

  • Fruit an aggregate of follicles