Botany Exam 4

chapters 22-24

Gymnosperm

refers to the exposed nature of the seeds; seeds produced on surface of sporophylls instead of enclosed within a fruit as in flowering plants

Seed

protective seed coat; supply of food for embryo; capable of dormancy in unfavorable environmental conditions

Pollen Grains

pollen cones produce these; consists of four cells and a pair of air sacs; air sacs add buoyancy in wind; develop from microspores

Nucellus

inside the female gametophyte in the ovule; enclosed in integument

Integument

becomes the seed coat after fertilization; surrounds the megasporangium; has a pore called micropyle

Pinophyta

pines, firs, spruces, cedars; most economically important phylum; contains over 100 species G

Ginkgophyta

has a single living representative, Ginkgo; tree with fan-shaped leaves; seeds enclosed in fleshy covering

Cycadophyta

leaves superficially palm-like

Gnetophyta

three genera; wood with vessels (only hardwood of the group)

Pines (Pinus)

dominant trees in coniferous forests of Northern Hemisphere; leaves needle-like and arranged in clusters of two to five leaves; cluster=fascicle; have modifications that enable them to survive harsh conditions

Bristlecone Pine

the world's oldest known living organisms

Fascicle

cluster; short shoots that have restricted growth

Pines: Structure and Form

hypodermis located below the epidermis, one to two layers of thick-walled cells; thick cuticle; recessed or sunken stomata; resin canals; mycorrhizal fungi associated with roots of most conifers; wood consists entirely of tracheids

Resin

antiseptic; prevents development of fungi; deters insects

Conifer wood

softwood; thick-walled cells absent

Broadleaf tree (dicot) wood

hardwood; thick-walled vessels and fibers present

Pines: Reproduction (1st type)

two kinds of spores produced; pollen cones (male strobili) consist of papery or membranous scales; microsporangia in pairs toward bases of scales (1st type); meiosis produces microspores that then develop into pollen grains; pollen grain consists of four cells and a pair of air sacs; air sacs add buoyancy in wind

Pines: Reproduction (2nd type)

megaspores in megasporangia within ovules; pair of ovules at bases of seed cone scales; seed cones larger than pollen cones, have woody scales with inconspicuous bracts between; ovule contains a megasporangium containing a nucellus and a single megasporocyte; megasporocyte undergoes meiosis, producing four megaspores (3 degenerate, 1 develops into the female gametophyte with archegonia at micropyle end)

Pines: Reproduction Cycle (1st year)

Seed cones take two years to mature
first year: pollen grains catch on sticky pollen drops oozing out of micropyle; pollen grain produces pollen tube that grows through nucellus; two sperm produced in pollen tube, mature male gametophyte=germinated pollen grain with pollen tube and two sperm, sperm have no flagella and no antheridium is formed; megaspore develops

Pines: Reproduction Cycle (2nd year)

Seed cones take two years to mature
second year: female gametophyte and archegonium mature; pollen tube arrives at archegonium; one sperm unites with egg, forming zygote (other sperm degenerates); embryo nourished by female gametophyte; integument becomes seed coat

Yew (Taxus) and California nutmeg (Torreya)

other conifers; produce ovules singly at tips of shoots; each ovule at least partially surrounded by cuplike aril

Aril

fleshy nucellus found in some conifers (Yew and California nutmeg)

Junipers

seed cones fleshy

Southern Hemisphere confier

Merkus pine; Podocarpus--fleshy-coated seeds with large appendage at base

Phylum Ginkgophyta -- Ginkgo

maidenhair tree; only one living species and only exists in cultivation;
leaves: notched, broad, fan-shaped leaves; leaves on short, slow-growing spurs; no midrib or prominent veins; hair-like veins branch dichotomously; deciduous;
life cycle similar to pines; dioecious; seeds enclosed in fleshy seed coat with unpleasant odor

Dioecious

male and female structures on separate trees

Phylum Cycadophyta -- The Cycads

slow-growing plants of tropics and subtropics; tall unbranched trunks; crown of large pinnately divided leaves; life cycle similar to conifers: pollination sometimes by beetles, dioecious, has pollen and seed strobili

Phylum Gnetophyta -- The Gnetophytes

unique among the gymnosperms in having vessels in the xylem; joint firs (Ephedra) - shrubby plants of drier regions of southwestern North America; Gnetum - vine-like plants with broad leaves in tropics; Welwitschia - only one species, confined to deserts of southwestern Africa, short stem and long taproot, only two straplike leaves that become tattered and split, dioecious, has male and female strobili

Pine Life Cycle

Angiosperms

flowering plants (vessel seed)

Carpel

encloses seed

Pistil

composed of a single carpel, or two or more united carpals

Ovule vs Ovary

seed develops from ovule within carpel; ovary becomes the fruit

Heterosporous

produces microspores (male) and megaspores (female)

Phylum Magnoliophyta -- the Flowering Plants

heterosporous; sporophytes dominant; female gametophytes wholly enclosed within sporophyte tissue and reduced to only a few cells; at maturity, male gametophytes consist of a germinated pollen grain with three nuclei

Development of the female gametophyte in Phylum Magnoliophyta

diploid megasporocyte differentiates in ovule; outer two layers of ovule differentiate into integuments that later become the seed coat; micropyle at one end of the ovule; 8 nuclei form two groups, four near each end of the cell; one nucleus from each group migrates to cell middle and forms central cell; cell walls form around remaining six nuclei--egg and two synergids closest to micropyle; three antipodals at opposite

Megasporocyte in Phylum Magnoliophyta

diploid; differentiates in ovule; undergoes meiosis and produces 4 haploid megaspores, 3 of which degenerate and the remaining cell enlarges and nucleus divides to produce 8 nuclei (without walls)

Female gametophyte of phylum magnoliophyta

megagametophyte, embryo sac; large sac containing 8 nuclei and 7 cells

Development of the male gametophyte in Phylum Magnoliophyta

formation takes place in anthers; four patches, corresponding to pollen sacs, of microsporocyte cells differentiate in anther; each microsporocyte undergoes meiosis to produce quartet of haploid microspores; microspores undergo three important changes (see other flashcard); generative nucleus will later divide to produce two sperm

Three important changes of the microspores of male gametophytes in phylum magnoliophyta

1. divide once by mitosis to form a small generative cell inside the larger tube cell; nucleus of tube cell = vegetative nucleus
2. members of each quartet of microspores separate
3. wall becomes two-layered; outer layer = exine--finely sculptured, contains chemicals that may react with chemicals in stigma

Life Cycle of Phylum Magnoliophyta

Pollination

transfer of pollen grains from anther to stigma;
self-pollination: pollen grains germinate on stigma of same flower; pollination by insects, wind, water, animals, or gravity

Fertilization

Union of sperm and egg

fertilization and development of the seed in phylum magnoliophyta

after pollination, further development of male gametophyte may not take place unless the pollen grain is a) from a different plant of the same species and b) from a variety different from that of the receiving flower; pollen tube grows between cells of stigma and style until it reaches ovule micropyle; vegetative nucleus stays at tips of pollen tube while generative cell lags behind and divides into two sperm; pollen tube enters female gametophyte, destroying synergid in the process, and discharges sperms

Mature male gametophyte in Phylum Magnoliophyta

germinated pollen grain with its vegetative nucleus and two sperms within tube cell

Double fertilization

one sperm unites with egg, forming zygote, then embryo; other sperm unites with central cell nuclei producing triploid endosperm nucleus that develops into endosperm tissue; endosperm becomes extensive part of seed in some monocots such as corn and other grasses; endosperm absorbed into cotyledons in most dicots

Endosperm tissue

nutritive tissue for embryo

Apomixis

without fusion of gametes but with the normal structures otherwise being involved; embryo may develop from diploid nutritive cell (2x) or other diploid cell of ovule, instead of from zygote; results in a vegetatively propagated plant

Parthenocarpy

fruits develop from ovaries with unfertilized eggs; results in seedless fruits (ex: navel oranges and bananas)

Superior ovary (hypogynous flower)

ovary produced on top of receptacle; other flower parts attached around ovary base

Superior ovary (perigynous flower)

flower parts attached to corolla tube of fused petals, creating floral tube that is not attached to ovary

Inferior ovary (epigynous flower)

receptacle or other flower parts fused to ovary and grown up around it; calyx and corolla appear to be attached to top of ovary

Complete flower

has calyx, corolla, stamens, and pistil

Incomplete flower

corolla or other flower parts missing

Perfect flower

both stamens and pistil present

Imperfect flower

either stamens or pistil missing; monoecious and dioecious species

Imperfect flower: monoecious species

male and female imperfect flowers on the same plant

Imperfect flower: dioecious species

plant bears only male flowers and other plants bear only female flowers

Bee-pollinated flowers

COLOR:
generally brightly colored, mostly blue or yellow; often have lines or other distinctive markings which may function as honey guides to lead bees to nectar; bees see UV light (humans do not)

Beetle-pollinated flowers

ODOR:
strong, yeasty, spicy, or fruity odor; white or dull in color because beetles do not have keen visual senses; some do not secrete nectar, but furnish pollen or food on petals in special storage cells

Fly-pollinated flowers

ODOR:
smell like rotten meat; dull red or brown

Butterfly- and moth-pollinated flowers

FRAGRANCE:
often have sweet fragrances; white or yellow for night-flying moths; sometimes red, often blue, yellow, or orange for butterflies; nectaries at bases of corolla tubes or spurs for long tongues

Bird-pollinated flowers

hummingbirds and sunbirds; often bright red or yellow; little if any odor because birds do not have a keen sense of smell; large and part of sturdy inflorescence; copious amounts of nectar because birds are highly active; long floral tubes

Bat-pollinated flowers

primarily in tropics; open at night when bats are foraging; dull in color; large enough for bat to insert head or consist of ball-like inflorescence containing large numbers of small flowers

Orchid flowers

have pollinators among all types mentioned; some extraordinary adaptations; pollen grains produced in little sacs called pollinia with sticky pads at base; members of Ophrys have modified petal that resembles female bumble bee or wasp--male bees/wasps attracted to flower, pollinia deposited on their head

Herbaria

singular: herbarium; libraries of dried, pressed plants, algae, and fungi arranged and labeled

Methods of Plant Preservation

fungi and bryophytes dried and stored in small packets; plant press used for vascular plants; vascular plant specimens mounted on herbarium paper; specimens stored so retrieval of specimens is easily accomplished

Class Magnoliopsida

dicot class of phylum magnoliophyta

Class Liliopsida

monocot class of phylum magnoliophyta

Alphonse de Candolle

wrote "Origin of Cultivated Plants" in the 1880's; cultivated plants originated in areas where wild relatives grow

N. I. Vavilov

1916; plants were domesticated in geographic regions with high genetic diversity of wild relatives; majority of domesticated plants originated from mountainous regions

Jack Harlan

1950's; associated crop origins with regions

Six major regions of plant origins

near-eastern region, Chinese region, African region, South Asia and Pacific Islands, North America, South and Central America

Near-eastern region

Mediterranean, northern Europe; barley, wheat, peas, lentils, asparagus, beets, carrots, turnips, olives, cherries, plums, apricots, apples, onions, garlic, broccoli, lettuce, flax, pistachios

Chinese region

temperate and southern China; bamboo, peach, walnut, ginger, gourds, camphor, tea, soybean, buckwheat, horseradish, cucumber

African continent

mostly Ethiopia and West Africa; yams, sorghum, okra, sweet melons, coffee, some cotton

South Asia and Pacific Islands

sugar cane, eggplant, mango, banana, citrus, safflower, nutmeg, clove, cardamom, turmeric, black pepper, coconut, taro, rice, sesame, onion

North America

sunflower, cranberry, blueberry, tobacco

South and Central America

garden beans, corn, peanut, white potato, lima beans, cashew, pineapple, avocado, red pepper, tomato, cotton, cacao (chocolate), sweet potato, pumpkin, squash, rubber, vanilla, cassava

Dicot families

buttercup, laurel, poppy, mustard, rose, legume, spurge, cactus, mint, nightshade, carrot, pumpkin, sunflower

Monocot families

grass, lily, and orchid

The Buttercup Family -- Ranunculaceae

dicot; nearly all 1500 species are herbaceous; petal vary in number; numerous stamens; several to many pistils with superior ovaries;
*concentrated in north temperate and arctic regions; most at least slightly poisonous*

The Laurel Family -- Lauraceae

dicot; about 1000 species of tropical evergreen shrubs and trees; no petals but sepals sometimes petal-like; stamens in three or four whorls (anthers open by flaps that lift up);
*cinnamon, cassia, camphor, sassafras trees, sweet bay, avocado*

Cinnamon

lauraceae, laurel family; pulverized bark of small tree

Cassia

lauraceae, laurel family; east asian evergreen bark (like cinnamon)

Camphor

lauraceae, laurel family; cold remedies, insecticides

Sassafras trees

lauraceae, laurel family; native to eastern U.S.

Sweet Bay

lauraceae, laurel family; flavoring in meat dishes

The Poppy Family -- Papaveraceae

dicot; herbs of temperate and subtropical regions; numerous stamens, but single pistil; milky or colored sap; opium poppies: opium-white fluid from capsules, morphine and codeine-heroin, papaverine and noscapine, poppy seeds;
*all species produce alkaloidal drugs*

The Mustard Family -- Brassicaceae

dicot; nearly all 2500 species in temperate and cooler regions of North America; four flower petals arranged in a cross; six stamen--2 short and 4 long; fruits = siliques or silicles; all produce pungent watery juice;
*many cultivated edible plants*

Cultivated edible plants of the mustard family

(brassicaceae) cauliflower, brussels sprouts, broccoli, radish, turnip, horseradish, watercress, rutabaga; Mustard -- ground seeds of two species of Brassica

The Rose Family -- Rosaceae

dicot; more than 3000 species of trees, shrubs, and herbs; flowers have basal parts fused into cup with petals, sepals, and numerous stamens attached to the cup's rim; family subdivided into subfamilies on basis of flower structure and fruits;
*enormous economic impact*

Economic impact of the rose family

(rosaceae) stone fruits: cherries, apricots, peaches, plums
pome fruits: apples, pears
aggregate fruits: strawberries, blackberries, raspberries
garden ornamentals: roses
fragrances
fruits of roses = hips -- Vitamin C

The Legume Family -- Fabaceae

*third largest of flowering plant families with 13,000 species*
dicot; cosmopolitan-grows globally in many diverse environments; flowers radial to bilateral; stamens fused into tube around ovary; fruit is a legume; important crop plants: peas, beans, soybeans, peanuts, alfalfa, sweet clover, licorice, carob
*fix nitrogen from the air*

The Spurge Family -- Euphorbiaceae

dicot; in tropical and temperate regions; several economically important plants: *cassava--staple food in tropical regions, *para rubber tree--crude rubber from latex of inner bark; stamens and pistils produced in separate flowers; flowers often inconspicuous and lack corolla (ex poinsettia)

The Cactus Family -- Cactaceae

dicot; more than 1500 species **native only to Americas** in dry, subtropical regions; leaves reduced in size, often spines; fleshy stems

The Mint Family -- Lamiaceae

dicot; 3000 species; unique combination of angular stems, **square in cross section**, opposite leaves, bilaterally symmetrical flowers; ovary superior and four-parted developing into four nutlets; plants produce mint oils which are used medicinally and as antiseptic

Mint Oils

(lamiaceae) rosemary, thyme, sage, oregano, marjoram, basil, lavender, catnip, peppermint, spearmint

The Nightshade Family -- Solanaceae

dicot; 3000 species concentrated in tropics of central and south america; flowers have fused petals with stamens fused to corolla; superior ovary develops into berry or capsule;
*food: tomato, white potato, eggplant, peppers, tobacco, petunia*

Poisonous Nightshades

many nightshades are poisonous, several have medicinal properties; belladonna drug complex: atropine-shock treatment and pain relief, scopolamine-tranquilizer; capsicum from red pepper-gastric stimulant; jimson weed-asthma; tobacco