Plant Systematics Exam 2

Water lilies, magnolias, and relatives

• Not a monophyletic group, Similar in morphology

• Number of floral parts is variable

• Flower whorls are often poorly differentiated.

  • Floral parts may be arranged in spirals rather than distinct whorls.

• Flowers often have strong odors - STANK!

Monocots

• Monophyletic

• ONE cotyledon

• Parallel leaf venation

• Flower parts in multiples of 3

• never woody

• Ex: grasses (Poaceae), sedges (Cyperaceae), lilies, orchids, palms

Dicots (Rosids & Asterids)

• TWO cotyledons

• netted leaf venation

• flower parts in multiples of 4 or 5

Rosids VS Asterids

• Rosids: petals not fused; more stamens than petals and not fused to petals; carpel number usually 3–5

• Asterids: petals usually fused (connate); stamens equal to or fewer than petals and adnate to petals; usually 2 carpels (often 2 locules)

Key Differences between major groups (Monocots, Dicots, Rosids, Asterids)

Flower Formulas - key points

P = parienth that is indistinguishable

Calyx #, Corolla (A or Z) #, Androecium #, Gynoecium #

circle around = fusion, dashed circle = sometimes

line beneath G = superior ovary, line above = inferior

lines connecting parts = adnate fusion

Graminoid Monocots

• “grass-like”

• Juncaceae, Cyperaceae, Poaceae

• small wind pollinated flowers often

Juncaceae - veg

Rush family

• Herbaceous; often rhizomatous and clump-forming.

• Leaves usually basal

• **Rushes are round

• Stems often hollow or partitioned.

Juncaceae - reproduction

• Inflorescence: congested cyme.

• usually 3-merous, radial, and bisexual.

• Fruit: capsule (splits at 3 seams)

Cyperaceae - veg

Sedge family

• Herbaceous; sometimes rhizomatous, often clumped

• Stems solid and often triangular.

• Leaves in three ranks

• Leaf sheaths closed.

**Sedges have edges

Cyperaceae - reproduction

• Flowers highly reduced; one scale-like bract below each flower. Perianth absent or hair-like.

• Stamens & carpels 3-merous

• Often monoecious

• Fruit: achene

Poaceae - veg

Grass Family

• Herbaceous; stem internodes often hollow (node is below leaf)

• Leaves in two ranks; leaf sheaths open; leaves have ligules (flaps of tissue or hairs).

• **Grasses have lashes (ligules)

Poaceae - reproduction (Spikelets)

• Inflorescence: spikelets, arranged in spikes or panicles.

• Fruit: caryopsis (grain).

• Spikelet: 1+ flowers and bracts.

• Glumes: bracts at the base of the spikelet.

• Lemma (lower) and palea (upper): bracts below each flower.

• Floret: one flower together with its lemma and palea.

• Lodicules are highly reduced perianth structures.

• Flowers usually perfect, typically with 3 stamens and 2 carpels.

Juncaceae vs. Cyperaceae vs. Poaceae

Ranunculaceae - veg

Buttercup Family

• Herbaceous; some vines/lianas

• Leaves variable: alternate or opposite, simple or divided.

Ranunculaceae - reproduction

• Inflorescence a cyme or flowers solitary. Flowers usually large and radial.

• Perianth often of petal-like tepals; sometimes sepals and petals distinct.

• Many stamens and usually many simple pistils.

• Fruits: aggregate of achenes or follicles.

Vitaceae - veg

Grape Family

• Woody vines = lianas

• Leaves alternate, usually palmately lobed or compound; sometimes pinnately divided.

• Tendrils positioned opposite the leaves (modified inflor)

Vitaceae - reproduction

• Inflor: cyme, positioned opposite the leaves.

• Flowers small and radial; plants often monoecious.

• Sepals inconspicuous

• Petals often fall off as the flower opens, sometimes fused at their tips.

• 2 fused carpels (compound pistil), ovary superior.

• Fruit: berry; two seeds per locule, usually four per berry. Seeds have a raphe (raised line)

Rosaceae - veg

Rose family

• Herbs, shrubs, trees

• Leaves: alternate, simple or pinnate

• Stipules present, often adnate to petiole

• Armature

Ex: raspberries, roses, cherries, apples…

Roseaceae - Reproduction

• Flowers: racemes, often large, radial, 5- merous

• Hypanthium

• Many stamens

• Carpels = 5+

• Fruits → diverse: aggregate, achenes, follicles, drupes, accessory fruits (enlarged hypanthium/receptacle)

• **Apomixis: asexual reproduction, seeds without fertilization

Fabaceae - veg

Pea Family

• usually vines (in VT), shrubs, trees

• Leaves: alternate, pinnately compound, stipules present

• Often terminal leaflet → tendrils

• **Nitrogen fixation → bacteria in root nodules convert N to ammonia, helps plant grow in N-poor env

Fabaceae - reproduction

• Inflor: Single or raceme

• “Faboid” type flowers

• 5-merous, zygomorphic (bilaterally sym)

  • 1 banner (top), 2 wings, 2 keel petals (fused)

• 10 stamens

• Hypanthium

• Fruit: legume or loment

Fabaceae Floral formula

Brassicaceae - veg

Mustard family

• Herbaceous

• Leaves: alternate, often basal, simple, sometimes lobed

• No stipules

• Mustard oils → strong smell & taste

Brassicaceae - reproduction

• Inflor: racemes usually

• Flowers: small/med sizes, yellow/white, radial, 4-merous

• 6 stamens (2 shorter outer, 4 longer inner)

• 2 carpels, superior

• Fruit: Silique/silicile (specialized capsule)

  • Replum - thin membrane separating the 2 locules, formed from placenta, persists after dehiscence

Brassicaceae floral formula

Onagraceae - veg

Evening Primrose family

• Herbs & shrubs

• Leaves: alternate or opposite, simple

• Stipules - absent or very small

• Hairy often

Onagraceae - reproduction

• Infor: racemes, 4-merous, radial

• Sepals reflexed (bent backward)

• Petals yellow/pink

• Hypanthium = large, elongate

• Ovary inferior (4 fused carpels)

• Fruit: capsule

Caryophyllales synapomorphy

Betalains (producing beet-red color)

Caryophyllaceae - veg

Carnation Family

• Herbaceous

• Leaves: opposite, simple, entire

• Swollen nodes

Caryophyllaceae - reproduction

• Inflor: cyme

• Sepals usually fused (balloon-like in Silene)

• No petals, rather petal-like structure is modified stamens (notched tips, 2 lobed because of anthers)

• Fruits: capsules, opens by apical teeth, free-central placentation

Polygonaceae - veg

Knotweed Family

• Herbaceous

• Leaves: alternate, simple

• Nodes swollen (polygon = multi joints)

• Ocrea: sheathing stipule (papery, wrapped around stem)

• Oxalic acid → sour taste

Polygonaceae - reproduction

• Inflor: raceme or spike, flowers small

• Tepals - petals & sepals near identical

  • 1 whorl of 5 OR 2 whorls of 3

• Fruit: achene, often winged

  • Basal placentation

  • **BUT derive from compound pistil but produces single seeded achene

Laminales characteristics

leaves: usually opposite

flowers: bilaterally symmetrical, 2 “lips” of petals (2 on top, 3 below)

stamens: 4 usually

Lamiaceae - veg

Mint family

• Herbaceous

• Leaves: opposite, simple, entire/toothed

• Square stems

• glandular hairs

• very fragrant → minty!

Lamiaceae - reproduction

• Inflor: spike-like or axillary

• Sepals: fused

• Petals: 5, fused, forming 2 lips

• Stamens: 4 didynamous (2 diff lengths - upper is shorter, below is longer)

• Carpels: only 2 but deeply 4-lobed pistil, superior, style gynobasic (at base of gynoecium),

• Fruit: schizocarp, producing 4 nutlets

Lamiaceae floral formula

Plantaginaceae - veg

Snapdragon family

• Herbaceous

• Leaves: opposite (or alternate), simple

• Round stems

Plantaginaceae - reproduction

Inflor is variable, small to large flowers

• 4-5 Sepals, fused

• 5 Petals, 2 “lips” formed

• 4 Stamens (didynamous - 2 lengths), often additional staminode (sterile stamen)

• Carpels: 2 fused, superior

• Terminal styles

• Fruits: many-seeded capsule (spooky af)

Asteraceae - veg

• Herbs in VT, shrubs, trees

• Leaves: alternate, opposite, whorled, simple often hairy

• Strong smelling (terpenoids)

Asteraceae - reproduction

• Flower = heads, capitulum (many small flowers)

  • head surrounded by involucre made of bracts (phyllaries)

• Sepals - modified into pappus (w/ bristles, hairys, awns)

• Petals - 5, fused

• Stamens - 5, filaments adnate to corolla, anthers connately fused

• Carpels - 2

• Fruit: achene (cypsela), basal placentation, pappus at tip often, inferior ovary

Asteraceae Flower Development

1. Stamens form tube

2. Style & stigma push through tube

3. Pollen presented to pollinators

4. Stigma matures later

3 Asteraceae Flower Types

Disc: radially symmetrical, usually perfect

Ray: bilaterally symmetrical, sterile or pistillate

Ligulate: bilaterally symmetrical, usually perfect

3 Asteraceae Head Types

Discoid head: only disc flowers (ex: artichokes, thistles)

Radiate head: disc & ray flowers (ex: sunflower)

Ligulate head: only ligulate flowers (ex: lettuces, see image)

Apocynaceae - veg

Milkweed family

• Herbs in VT

• Leaves: opposite, whorled, simple

• Latex - very toxic

Apocynaceae - reproduction (inflorescence)

• Inflor = cyme usually

• **highly modified stamens/carpels make up most of flower

• 2 simple pistils (carpels), fused only at stigma, plate-like

• gynostegium: fused anther & stigma

• hoods (where nectar pools), stigmatic slit where pollinia are, bugs get stuck

• Fruits: paired (simple, 1 per ovary) → follicles, berry, drupe

  • seeds with floofy hairs

  • free-central placentation