UTA Plant Science Exam 1

Bryophyte characteristics

nonvascular (no leaves, roots, or shoots) , gametophyte dominant, motile sperm that require water for fertilization, SEEDLESS

hydroids

bryophyte water conducting tissue, NOT lignified

thalloid (thallus)

leaf-life structures used for uptake of water and gas exchange

bryophyte solution to no stems

cuticle with structures analogous to stomata (gas exchange)

rhizoids

bryophyte “roots” used to Anchor but NOT FOR WATER TRANSPORT

where do bryophytes absorb water

absorption of water and ions occur directly and rapidly throughout the [gametophyte]

dominant generation of bryophytes

gametophyte

gametophyte

gamete producing generation

sporophyte

spore producing generation

alternation of generations diagram

antheridium

male gametangia, either unicellular or multicellular, consists of: Stalk (antheridiophore), Sterile Jacket Layer (single cell layer), Spermatogenous Tissue (each spermatogenous cell forms one biflagellated sperm cell)

archegonium

female gametangia, multicellular, consists of: Neck and Neck canal cells, Venter (surrounds single egg), fertilization occurs inside here

fertilization in bryophyes

occurs in archegonium, neck canal cells disintegrate forming a fluid-filled tube, sperm travels down archegonium and down to the neck, fuses with egg to form zygote, zygote remains in archegonium, undergoes mitosis to generate the embryo, eventually becomes mature sporophyte

embryophytes

term for ALL plants

matrotrophy

embryo gets nutrients and protection from maternal gametophyte, “placenta” between the two generations facilitate the transfer of nutrients

mature sporophyte

unbranched, has single sporangium (Foot, Seta, Capsule), spores are released when conditions are favorable

elaters

from mature sporangium, are elongated cells, contain moisture absorbing wall thickenings, when capsule dehisces, elaters dry and undergo twisting motion that helps disperse spores

sporopollenin

impregnates spore walls, decay/chemical resistant, survival during air transport

protonemata (protonema)

spores germinate to often form this juvenile stage of the gametophyte, formed in ALL mosses, and some liverworts

phylum marchantiophyta

liverworts

phylum anthocerophyta

hornworts

bryophyta

mosses

[Liverworts]

[Marchantiophyta], no hydroids, single celled rhizoid, sporophyte embedded in gametophyte, consists solely of spherical capsule, gametophytes unisexual, gametophores produce gametangia, some are capable of asexual reproduction, gemmae are multicellular and produce multicellular gametophyte, dispersed by splashes of rain

[Hornworts]

[Anthocerotophyta], no hydroids or leptom, unicellular rhizoid, nostoc cyanobacterium nitrogen fixing in gametophytes, sporophytes have cuticle, lack seta (meristem instead), elongates sporangium when favorable conditions, pseudoelaters ribbonlike dehiscence

Bryophyta: Sphagnidae

peat mosses, unusual protonema (budlike, divides in three), peculiar gametophyte (mop head, hyaline cells), lack rhizoids, water holding up to 20x their dry weight, explosive spore dispersal (operculum and pseudopodium), used in horitculture, antiseptic, peatlands 1-3% of earth, carbon cycle

Bryophyta: Andreaeidae

granite mosses, protonema stage, split create slits to disperse spores when dry,

Bryophyta: Bryidae

“true mosses”, protonema juvenile, multicellular rhizoids, hydroids are like tracheids (dead at maturity), not lignified, leptoids in some, unbranched sporophyte => embedded in gametophyte placenta, have stomata, peristome uncurl in dry air, curl in moist

what do bryophytes and vascular plants have in common?

multicellular matrotrophic embryo, heteromorphic alternation of generations, trace back to green algae

adaptations of vascular plants

1. lignin: grow large on land, conducting tissue, vertical support

2. apical meristem: allows for branching

3. dominant sporophyte

4. branched sporophyte: multiple sporangia

evolution of vascular plant body

gametophyte becomes REDUCED and dependant on the sporophyte

tracheary elements

conducting cells of xylem, contain lignin, resistant to degradation, provides stem support

tracheids

Silurian and Devonian, only type of water-conducting cells in most plants, trend in thickening from annular rings to pitted

vessel elements

principle water-conducting cells in angiosperms, evolved independently (convergent evolution)

stele

central cylinder of tissue composed of primary vascular tissue and sometimes pith (vascular cylinder)

protostele

ANCIENT, found in most roots, solid cylinder of vascular tissue, no pith, extinct seedless vascular plants, in some living vascular plants

siphonostele

central pith surrounded by vascular tissue, most species of seedless vascular plants, convergent from protostele

eustele

discrete strands around a pith, almost ALL seed plants, evolved directly from protostele (i.e., none of the seedless vascular plants with living representatives gave rise to the seed plants)

evolution of roots

believed to evolved from subterranean portions of axis of ancient vascular plants

evolution of leaves

arise as leaf primordia from apical meristem

• microphylls

• megaphylls

microphylls

one strand of vascular tissue or vein, characteristic of lycophytes, associated with protosteles

megaphylls

each blade has complex system of branching veins, associated with siphonosteles or eusteles

evolved through 3 transformations

1. overtopping: formation of determinate lateral branches

2. plantation: development of “flattened” branch systems

3. webbing: fusion of planated branches with lateral growths of photosynthetic mesophyll tissue to form blade

homosporous

free living gametophyte, relies on water to transfer sperm, produce one kind of spore from meiosis, bisexual spore, turns into bisexual gametophyte, gametophyte develops outside the spore wall, some lycophytes, fern allies, and almost all ferns

heterosporous

two spores types in two different types of sporangia

• microspores (n) borne in microsporangia (2n)

• megaspores (n) borne in megasporangia (2n)

result in unisexual gametophyte

• reduced in size, develops within spore wall

reduced gametophyte retained in spore wall, dependent on sporophyte for nutrition

gametophyte reproductive evolution

trend towards smaller, simpler gametophytes

phylum rhyniophyta

extinct, terminal sporangia, homosporous, sporophyte dominant, alternation of isomorphic generations, simple dichotomously branching stems, Cooksonia oldest vascular plant

phylum zosterophyllophyta

extinct, leafless, dichotomously branched, stems with cuticle, only upper stems had stomata, homosporous, downward growing branches function like roots supporting lateral growth

phylum trimerophytophyta

extinct, larger more complex, leafless, homosporous, ancestral to both ferns and pro-gymonosperms, large vascular strand => taller

phylum lycopodiophyta

1200 living species, all herbaceous, differentiated into roots, stems, leaves, all possess microphylls

family lycopodiaceae

club mosses, sporophyte, stem and root are protostelic, sporangia found on sporophylls (fertile microphylls), grouped in to strobili, homosporous, bisexual spores => bisexual gametophytes, requires water for fertilization, sporophyte becomes independent

family selaginellaceae

spike mosses, microphylls, stem and root are protostelic, tropical, sporophyills arranged in strobili, heterosporous:

• megasporangia are borne on megasporophylls

• microsporanga are borne on microsporophylls

water required for fertilization, resurrection plant

phylum monilphyta

horsetails, oldest surviving genus, scouring rushes, jointed stems and rough texture, microphylls, homosporous, free-living gametophytes, bisexual,

fiddleheads, abaxial sporangia, siphonostelic rhizomes, megaphylls, circinate vernation => protects embryonic leaf tip during development, possess sori (sporangia clusters), free-living, bisexual gametophytes, prothallus - heart shaped and has rhizoids, water required for sperm,

eusporangiate

having a sporagnium developed from a group of cells rather than a single cell

oogamous

condition in which small sperm that travels (or is conveyed) to Egg

strobili

sporophylls clustered into cone-like structures

all seed plants are ________

heterosporous

megasporocyte/microsporocyte

specific cells that undergo meiosis to produce spores

• housed in their respective sporangium

• megaspore/microspore => mitosis => megagametophyte/microgametophyte

evolution of the seed

production of seed is extreme form of heterospory

• megasporangia and megaspore are modified to form an ovule which develops into a seed

ovule

baby seed, consists of megasporangium which contains megasporocytes that produce megaspores, surrounded by integuments

• develops into seed

seed

mature ovule that contains an embryo, food stores, and coat

gymnosperm

naked seed, ovules and seeds exposed on surface of sporophylls

• contain megagametophyte

no water for fertilization required

• male gametophyte (pollen) transfered to female gametophyte (pollenation)

microgametophyte

develop as pollen grains, transferred to vicinity of megagametophyte = pollination

• produce a pollen tube that brings non-motile sperm directly to egg via micropyle (opening)

• NO NEED FOR WATER TO FERTILIZE!

phylum coniferophyta

cones, drought-resistant

genus pinus

seedlings: needlelike leaves in spiral, single, then in bundles (fascicles), leaves adapt for low moisture, thick cuticle, hypodermis, sunken stomata, retain leaves for 2-4 years, xylem primarily tracheids

pinus life cycle

takes up to 2 years, separate cones for male (lower) female (higher), meiosis in early spring

pinus male reproductive

• microsporangia on sporophylls

• microsporocytes (microspore mother cells)

produce 4 haploid microspores => each undergoes mitosis to become pollen grain

• two prothallial cells

• one generative cell

• one tube cell

• this is the immature male gametophyte (microgametophyte)

4 celled pollen grain (mature)

pinus female reproductive

megasporangiate (ovulate), seed scale complex (modified branch system) includes:

• ovuliferous scale with two ocules on upper surface

• subtending sterile bract

multicellular nucellus (megasporangium) that contains one megasporocyte (megaspore mother cell)

massive integument with opening (micropyle)

• after meiosis, only one megaspore is functional

pinus pollination

occurs in spring, scales on ovulate cones widely separated, pollination drops secreted by ovulate sticks to pollen and draws in pollen grain, scales close after pollination

• tube cell elongates, produces 1 sterile cell + 1 spermatogenous cell

• spermatogenous cell later divides to make 2 sperm cells

pinus fertilization

~15 months after pollination, pollen tube reaches egg cell in archegonium

one sperm will fertilize the egg

pinus seed

usually shed in fall of 2nd year

• most winged (wind dispersal)

• some pines need fire to open

• some require birds

other important conifers

Cupressaceae: redwoods, sequoia sempervirens, juniper (cedars), bald cypress, pond cypress,

phylum cycadophyta

palmlike plants, tropical subtropical, zamia integrifolia,

• coralloid roots: grow upwards and branch dichotomously near soil surface

highly toxic, unisexual reproductive units

phylum gingkophyta

gingko biloba, fan shaped leaves, unisexual, female seeds stinkay, doug russell park

phylum gnetophyta

gnetum, ephedra, welwitschia, resemble angiosperms, produce “nectar”, double fertilization, strobili look like flower clusters

ephedra

branched shrubs with small, scalelike leaves, arid regions, only genus of gentophytes found in US

welwitschia

one species, two leaves only but split into several parts when growing, mostly buried in sand, coastal desert of southwestern Africa

• dioecious

angiosperms

flowering plants, double fertilization! one phylum anthophyta

monocot (monocotyledons)

• one cotyledon

• fibrous roots

• scattered vascular system

• parallel veins in leaf

• flowers are in multiples of 3

• grasses, lilies, irises, orchids, palms

dicot (eudicotyledons)

• two cotyledeon

• tap roots (thick main)

• ringed vascular system

• net-like veins in leaf

• flowers are in multiples of 4 or 5

• most trees, shrubs, many herbs

myco-heterotrophs

lack chlorophyll, obligate relationship with fungi, “mycorrhizal cheater” (steals from fungi)

the flower

determinate shoot that bears sporophylls

inflorescences

flower bearing branches of plant

peduncle

fat meaty main stalk

pedicel

small part, stalk of individual flower on clustered inflorescences

spike inflores

simple umbel inflores

compound umbel inflores

head inflores

disc vs. ray flowers

disc: small

ray: big

the four whorls

1. sepal

2. petal

3. stamen (male)

4. carpel (female)

2 sterile whorls (perianth)

1. calyx - made of sepals

2. corolla - made up of petals

• toyota corolla has “pedals”

2 fertile whorls

androecium: made of stamen

• microsporophylls

• filament

• anther containing pollen sacs two pairs

gynoecium: made of carpels

• megasporophylls

• ovary: houses ovule

• style: connects stigma to ovary

• stigma: pollen receptacle

complete vs incomplete

all four whorls (sepals, petals, stamen, carpel) present

• if any missing it is Incomplete

• based on number of whorls ONLY!

perfect vs imperfect

perfect contains both female and male parts

imperfect: unisexual, one sex only

• staminate flower: male

• carpellate flower: female

based on sex ONLY!

monoecious

plant has both male and female flowers (doesn’t have to have both parts on one flower)

dioecious

plant has either male OR female, but not both

parietal

axial

free-central

hypogynous

insertion point below ovary