Bio Ch 23 Flashcards
Plants
multicellular, photosynthetic eukaryotes whose evolution is marked by adaptations to a land existence
Charophytes
land plants are most closely related to freshwater green algae known as these
Whorls
clusters of branches that occur at multicellular nodes
Nodes
regions between the enlarged cells of the main axis where male and female reproductive structures grow
Apical
refers to the tip of a filament or branch
Alternation of generations
an organism has 2 alternating forms in the course of its life cycle
Spore
haploid reproductive cell that develops into a new organism without the need to fuse with another reproductive cell; undergoes mitosis and becomes a gametophyte
Embryophyta
because land plants protect their embryos, this is an alternate name for the clade
Sporophyte
2n generation; produces at least 1, and perhaps, several, multicellular sporangia
Sporangia (pl. sporangium)
produce spores by meiosis; have a wall that contains sporopollenin, a molecule that prevents drying out
Gametophyte
spores become a n generation called this; bears multicellular gametangia, which have an outer layer of sterile cells and an inner mass of cells that become the gametes
Antheridium
male gametangium
Archegonium
female gametangium
Cuticle
exposed parts of land plants are covered by an impervious waxy material called this, which prevents loss of water
Stomata (sing. stoma)
most land plants have these little openings that allow gas exchange, despite the plant being covered by a cuticle
Bryophytes
liverworts, hornworts, and mosses; first plants to colonize land; superficially appear to have roots, stems, and leaves (no vascular tissue); only land plant in which the gametophyte is dominant
Vascular tissue
specialized for the transport of water and organic nutrients throughout the body of the plant
Nonvascular plants
bryophytes; lacking in vascular tissue
Liverworts
2 groups: thallose (flattened bodies) and leafy (superficially resemble mosses); name derived from lobes of the thallus
Rhizoids
numerous hairlike extensions that project into the soil; serve in anchorage and limited absorption
Hornwort
usually grows as a thin rosette or ribbonlike thallus between 1 and 5 cm in diameter; some live on trees; majority live in moist, well-shaded areas; photosynthesize but also have a symbiotic relationship with cyanobacteria (which can fix nitrogen from the air); can bypass alternation of generations by producing asexually through fragmentation
Mosses
largest phyla of nonvascular plants (over 15,000 species); 3 distinct groups - peat, granite, true
Vascular plants
dominate the natural landscape in nearly all terrestrial habitats; ex. trees
Xylem
vascular tissue which transports water through the stem to the leaves; evolution essential to the evolution of trees
Phloem
another conducting tissue; transports nutrients in a plant
Lignin
material that strengthens plant cell walls
Seedless vascular plant
plant in which sporangia produce windblown spores
Lycophytes
club mosses, among the 1st vascular plants to evolve and to have leaves (microphylls); 3 groups - ground pines, spike mosses, quillworts
Microphylls
1 strand of vascular tissue; most likely evolved as simple side extensions of the stem
Rhizome
lycophytes’ roots come off this branching, underground stem
Sporophylls
microphylls that bear sporangia
Strobili (sing. strobilus)
sporophylls grouped into club-shaped terminal clusters
Homosporous
spores that germinate into inconspicuous and independent gametophytes; ex. ground pines
Heterosporous
ex. spike mosses, quillworts, and seed plants; have microspores that develop into male gametophytes and megaspores that develop into female gametophytes
Microspores
develop into male gametes
Megaspores
develop into female gametes
Pteridophytes
ferns, horsetails, whisk ferns; seedless vascular plants; have megaphylls
Megaphylls
broad leaves with several strands of vascular tissue
Horsetails
consists of 1 genus (Equisetum) and approximately 25 species of distinct seedless vascular plants; mostly inhabit wet, marshy environments around the globe; silica in cell walls so used to be called scouring rushes; still used as an ingredient in a few abrasive powders
Whisk ferns
genera Psilotum & Tmesipteris; can be found on epiphytes or on the ground; resemble a broom in Psilotum species (no leaves)
Epiphytes
plants that live in or on trees
Ferns
11,000 species; abundant in warm, moist, tropical regions; can also be found in temperate regions and as far north as the Arctic Circle; some live in dry, rocky places; others have adapted to aquatic life; range in size
Fronds
megaphylls of ferns; commonly divided into leaflets
Seed plants
vascular plants that use seeds during the dispersal stage of their life cycle
Seeds
contain a sporophyte embyro and stored food within a protective coat; allow for survival in harsh conditions during long periods of dormancy until environmental conditions become favorable for growth
Pollen grains
male gametophytes
Pollination
occurs when a pollen grain is brought into contact with the female gametophyte by wind or a pollinator
Pollen tube
sperm move toward the female gametophyte through a growing structure called this
Ovule
a megaspore develops into a female gametophyte within this structure, which becomes a seed following fertilization
Gymnosperm
cone-bearing seed plants; ovules not completely enclosed by sporophyte tissue at the time of pollination
Angiosperms
flowering plants; ovules completely enclosed within diploid sporophyte tissue (ovaries) which becomes a fruit
Conifers
575 species of trees, many evergreen, including pines, spruces, firs, cedars, hemlocks, redwoods, cypresses, yews, and junipers; name signifies plants bear cones
Cones
reproductive structure in conifers made up of scales bearing sporangia; pollen ones bear microsporangia, and seed ones bear megasporangia
Monoecious
a single plant carries both male and female reproductive structures
Cycads
10 genera, 140 species; distinctive gymnosperms; native to tropical and subtropical forests; commonly used in landscaping; ex. sago palm; trunk unbranched; have pollen and seed cones on separate plants; pollinated by insects rather than wind
Ginkoes
plentiful in fossil record; only 1 surviving species today; AKA maidenhair tree; dioecious; fleshy seeds ripen in the fall, give off a foul odor (male trees usually preferred for planting); resistant to pollution; seeds considered a delicacy in Asia; extract has been used to improve blood circulation; native to China
Dioecious
a single plant produces either male or female reproductive structures but not both
Gnetophytes
3 living genera; 70 species, very diverse in appearance; xylem is structured similarly, none have archegonia, strobili (cones) have similar construction; reproductive structures of some species produce nectar; insects play a role in pollination; ex. Ephedra, from which ephedrine is extracted
Angiosperms
flowering plants; exceptionally large and successful group of plants (240,000 known species = 6x number of all other plant groups combined); live in all sorts of habitats (fresh water, desert, frigid north, torrid tropics); range in size from tiny, almost microscopic duckweed to Eucalyptus trees over 100m tall; all fruits, vegetables, nuts, herbs, and grains included; ovules always enclosed within diploid tissues
Monocotyledones (monocots)
65,000 species; flowering plant group; members have 1 embryonic leaf (cotyledon), parallel-veined leaves, scattered vascular bundles, flower parts in threes or multiples of three, and other characteristics; ex. corn, tulips, pine-apples, bamboos, sugar cane
Eudicotyledones (eudicots)
175,000 species; true dicot; flowering plant group; members have 2 embryonic leaves (cotyledons), net-veined leaves, vascular bundles in a ring, flower parts in fours or fives and their multiples, and other characteristics; cacti, strawberries, dandelions, poplars, beans
Cotyledons
“seed leaves” that contain nutrients that nourish the plant embryo
Flowers
vary widely in appearance; reproductive organ of a flowering plant, consisting of several kinds of modified leaves arranged in concentric rings, and attached to a modified stem called the receptacle
Peduncle
flower stalk; expands slightly at the tip into a receptacle
Receptacle
at the top of the peduncle; bears the other flower parts
Sepals
Collectively called the calyx; protects the flower bud before it opens; may drop off or may be colored like the petals; usually green, remain attached to the receptacle
Petals
collectively called the corolla; quite diverse in size, shape, and color; often used to attract a particular pollinator
Stamens
2 parts - a saclike container (anther) and a slender stalk (filament); pollen grains develop from microspores produced in the anther
Carpel
vaselike structure with 3 major regions (stigma, style, ovary)
Stigma
enlarged sticky knob
Style
slender stalk
Ovary
enlarged based that encloses one or more ovules; ovule becomes seed; this becomes the fruit (instrumental in distribution of seeds)
Double fertilization
one sperm unites with an egg, forming a diploid zygote; the other unites with polar nuclei, forming a triploid endosperm nucleus
Fruit
derived from an ovary; in some instances it is an accessory part of the flower
