Botany Exam 4 (CH 18, 20, 21, 22)

euglena (euglenoids)

has no rigid wall and can change its shape as it moves. have a pellicle, gullet, and eyespot. asexual reproduction by cell division. sexual reproduction is suspected but never confirmed. can survive indefinitely.

coccolithophores

has scales formed of calcite crystals

albuminous cells

have the same functions as companion cells.

dioecious

having unisexual flowers or cones, with the male flowers or cones confined to certain land plants and the female flowers or cones of the same species confined to other different plants.

doctrine of signatures

held that any plant part that would resemble a human body part would be helpful in healing that body part if it were in pain.

peristome

one or two series of flattened, often ornamented structures (teeth) arranged around the margin of the open end of a moss sporangium; the teeth are sensitive to changes in humidity and facilitate the release of spores.

unaltered fossils

organisms fell into oil or water that lacked oxygen and did not permit decay. some animals died in snow fields and their bodies were permanently frozen. they are very rare.

nucellus

ovule tissue within which an embryo sac develops.

spermatium

part of the spermtangia. functions as a nonmotile male gamete.

sphagnum moss

peat moss. used by nurses to protect wounds in world war 1. has antiseptic properties, water absorbing "leaves".

stoneworts

phylum charophyta. freshwater. look like a horsetail plant. sexual reproduction is oogamous. male gametes are produced by multicellular structure.

downy mildew of grapes and late blight of potato are two diseases caused by

phylum oomycota.

pine

pinus. largest genus of conifers. have leaves that are needlelike and arranged in clusters from two to five leaves each.

wort

plant or herb.

agar

produced abundantly by gelidium. substance with the consistency of gelatin and used as a solidifier of nutrient culture media for the growth of bacteria.

oldest known seeds

produced by plants that appeared late in the devonian period more than 350 million years ago.

isocetes

quillworts. leaves (microphylls) are slightly spoon shaped. they are arranged in a tight spiral on a stubby stem. ligules occur towards the leaf bases. generally less than 10 cms but sometimes up to .6 meters. no strobili are formed. similar to spike mosses. both types of sporangia are produced at the bases of leaves. up to 1 million microspores may be produced in a single microsporangium. appeared in the cretaceous period.

volvox

representative line of green algae that forms colonies similar to those of chlamydomonas held together in secretion of gelatinous substance. the flagella of individual cells beat separately but pull the whole colony along. reproduction may be asexual or sexual.

phycologists

scientists who specialize in the study of algae.

ulva

sea lettuce. multicellular seaweed with flattened, crinkly edged blades that be 1 meter or more long. a basal holdfast anchors the blades, which may be haploid or diploid, to rocks.

resin

aromatic and antiseptic and prevents the development of fungi. deters insect attacks.

marchantia

asexual reproduction: reproduces asexually by means of gemmae (singular gemma). sexual reproduction: the gametangia are produced on separate male and female gametophytes. both gametangia are formed on gametophores.

holdfast

attachment organ or cell at the base of the thallus or filament of certain algae.

spermatogenous cell

a cell in conifers that produces two male gametes.

sori

a cluster of sporangia; the term is most frequently applied to clusters of fern sporangia.

sporocytes

a diploid cell that becomes four haploid spores ornuclie as a result of undergoing meiosis.

megasporocyte

a diploid cell that produces megaspores upon undergoing meiosis.

microsporocyte

a diploid cell that produces microspores upon undergoing meiosis.

capsule

a dry fruit that splits in various ways at maturity often along or in between carpel margins. the main part of a sporophyte in which different types of tissue develop.

Polysiphonia

a feathery red alga that is widespread in marine waters.

fronds

a fern leaf; term often applied to palm leaves.

algin

a gelatinous substance produced by certain brown algae; it is used in a wide variety of food substances and in pharmaceutical, industrial, and household products.

hypodermis

a layer of cells immediately beneath the epidermis and distinct from the parenchyma cells in the cortex in certain plants.

pteridosperms

seed ferns, reclassfied as gymnosperms.

isogamy

sexual reproduction in certain algae and fungi having gametes that are alike in size.

oogamy

sexual reproduction in which the female gamete, or egg, is non motile and larger than the male gamete, or sperm which is motile.

chlamydomonas

small, actively moving alga. an inhabitant of freshwater pools. unicellular slightly oval-shaped surrounded by a complex multilayered wall that is partially composed of glycoproteins. has a pair of whiplike flagella on one end that pulls it through the water. has two or more vacuoles near the base of the flagella that contract and expand (contractile vacuoles). has a single cup-shaped chloroplast that partially hides the centrally located nucleus. has one or two pyrenoids located in each chloroplast. most species also have a red eyespot on the chloroplast near the base of the flagella (the eyespot allows it to detect light). cells are haploid, however, these cells can undergo mitosis to produce genetically identical daughter cells through asexual reproduction. sometimes undergo sexual reproduction; pairs of cells in a mass will fuse to form diploid zygotes that remain dormant from days to months but once favorable conditions happen the zygotes undergo meiosis producing four genetically different haploid zoospores which grows into a full-sized Chlamydomonas cell.

microphylls

a leaf having a single unbranched vein not associated with a leaf gap. most microphylls are photosynthetic.

megaphylls

a leaf having branching veins; it is also associated with a leaf gap.

microsporophylls

a leaf, usually reduced in size on or within which microspores are produced.

megasporophylls

a leaf, usually reduced in size, that produces megaspores following meiosis.

diatomaceous earth

a light porous and powdery material that contains a bout 6 billion diatoms shells per liter. melting point of 1,750* C.

sperms

a male gamete; except for those of red algae and angiosperms, sperms are frequently motile and are usually smaller than the corresponding female gametes.

sporophylls

a modified leaf that bears sporangia or sporangium.

zoospores

a motile spore occuring in algae and fungi.

thallus (thalli plural)

a multicellular plant body that is usually flattened and not organized into roots stems or leaves.

vascular plants

a plant having xylem and phloem.

gymnosperm

a plant whose seeds are not enclosed within an ovary while in development. from greek words gymnos (naked), and sperma (a seed). the seed-bearing sporophylls of the sporophyte are often spirally arranged in strobili that develop at the same time as smaller pollen-bearing strobili. pollen cones produce pollen grains.

micropyle

a pore or opening in the integuments of an ovule through which a pollen tube gains access to an embryo sac or archegonium of a seed plant.

pinnae (singular: pinna)

a primary subdivision of a fern frond; the therm is also applied to a leaflet of a compound leaf.

conjugation

a process leading to the fusion of isogametes in algae, fungi, and protozoa; also y the means of which certain bacteria exchange DNA.

dulse

a red seaweed that became a famous substitute during the irish famine.

spores

a reproductive cell or aggregation of cells capable of developing directly into a gametophyte or other body without uniting with another cell. sexual spores formed as a result of meiosis are often called meiospores. spores produced mitosis may be referred to as vegetative spores.

filament

a row of cylindrical cells attached end to end to form a thread

slime mold

a simple organism that moves lime and amoeba but resembles a fungus when reproducing.

pyrenoid

a small body found on the chloroplasts of certain green algae and hornworts. associated with starch accumulation. proteinaceous structures associated with the synthesis of starch. may occur singularly on a chloroplast or numerously.

gemmae

a small outgrowth of tissue that becomes detached from the parent body and is capable of developing into a complete new plant or other organism. they are produced in cuplike structures on liverwort thalli and are also produced by certain fungi.

annulus

a specialized layer of cells around a fern sporangium; it aids in spore dispersal through a springlike action. also a membranous ring around the stipe of a mushroom.

megasporangia

a sporangium in which megaspores are produced.

microsporangia

a sporangium within which microspores are formed.

megaspores

a spore that develops into a female gametophyte.

microspore

a spore that develops into a male gametophyte.

antheridiophore

a stalk that bears an antheridium.

archegoniophore

a stalk that bears an archegonium.

elater

a straplike appendage (usually occurring in pairs) attached to a horsetail (equisetum) spore. somewhat spindle-shaped sterile cell occurring in large numbers in liverwort sporangia; both types of elaters facilitate spore dispersal.

pollen grains

a structure derived from the microspore of seed plants that develops into a male gametophyte.

sporangia

a structure in which spores are produced, maybe unicellular or multicellular.

closed system

a system in which no matter is allowed to enter or leave

conjugation tube

a tube permitting transfer of a gamete or gametes between adjacent cells.

pollen tube

a tube that develops from a pollen grain and conveys the sperms to the female gametophyte.

resin canals

a tubular duct of may conifers (pinophyta) and some angiosperms that is lined with resin-secreting cells.

chlorella

a widespread green alga that is easy to culture. scientists have turned them into portable oxygen generators.

selaginella (spike mosses)

abundant in the tropics. their leaves have an extra appendage called a ligule on the upper surface near the base. they produce two different types of spores and gametophytes. sporangia develop on either microsporophylls or megasporophylls. microsporophylls bear microsporangia containing numerous microsporocytes that undergo meiosis producing tiny microspores. the megasporophylls usually contain a megasporocyte that after meiosis becomes four comparably large megaspores. each microspore may become a male gametophyte consisting of antheridium within the microspore wall. either 128 or 256 sperm cells with flagella are produced in each antheridium. known as the resurrection plant

"leafy" liverworts

abundant in tropical forests and fog belts. no midribs. have folds and lobes. archegonia and antheridia are produced in cuplike structures composed of a few modified leaves. when a spore germinates it produces a protonema. the protonema matures into a mature gametophyte plant.

lignin

adds mechanical strength to cell walls and provides protection against microbes.

mold

after silt or other sediment has buried an object and hardend into rock, the organic material may be slowly washed away by water going through the pores of the rock leaving behind a space that can be filled with silica deposits. if only a space is left it is called a mold.

cast

after silt or other sediment has buried an object and hardend into rock, the organic material may be slowly washed away by water going through the pores of the rock leaving behind a space that can be filled with silica deposits. if the hole is filled with silica it called a cast.

strobili (singular: strobilus)

an aggregation of sporophylls on a common axis; usually resembles a cone or is somewhat cone shaped.

embryos

an immature sporophyte that develops from a zygote within an ovule or archegonium after fertilization.

aril

an often brightly colored appendage surrounding the seed of certain plants. ex. yew.

epiphyte

an organism that is attached to and grows on another organism without parasitizing it.

gametangia

any cell or structure in which gametes are produced.

fossil

any recognizable prehistoric organic object (or its impression) that has been preserved from past geological ages in the earth's crust. includes: teeth markings, borings, impressions of footprints and tracks, dung deposits, and deposits of chemicals that are evidence of the activities of quick burial enhances the chances or organic material being fossilized.

phylum lycophyta

club mosses and quillworts. the stems of these plants are covered with microphylls. used to be used to reduced fevers but had undesirable affects.

fascicle

cluster.

fucus

common rockweed. separate male and female thalli are produced.

plankton

free floating aquatic organisms that are mostly microscopic.

bladders

gas filled floats in the thallus

phylum ginkgophyta

ginkgo. notched , broad, fan-shaped leaves with veins that fork evenly are distinct among ginkgos. the mature seeds resemble small plums and are enclosed in a fleshy covering. only one species, ginkgo bilboa, exists within this phylum. name derived from chinese word "silver apricot". often referred to as maiden hair trees. can be used as food.

phylum gnetophyta

gnetophytes. a unique characteristic of gnetophytes is the presence of vessels and tracheids in the xylem. many members of superficially resemble flowering plants, although they still produce strobili. about 70 types of gnetophytes exist.

chlorophyta

green algae.

gullet

groove through which food can be ingested.

cryptomonads

group of asymmetrical somewhat flattened, unicellular marine and freshwater algae with two flagella. single two lobed chloroplast with starch granules surrounding a central pyrenoid. has a gullet and ejectosomes

phragmoplasts and cell plates

develop when plant and some algal cells divide.

photoreceptor

light-sensitive area.

auxospores

like any other zygotes except that the original size of the diatom is restored when the auxospores expand rapidly before rigid walls are formed.

phylum hepaticophyta

liverworts. gametophytes grow horizontally and have a flattened or leafy appearance (may resemble lobes of animal liver). gametophytes of some liverworts may cup like structures that produce propagules asexually, although sexual reproduction also takes place to produce the sporophyte. 20% thalloid liverworts, the rest "leafy" and resemble mosses. thalli or leafy stages (gametophytes) develop from spores. when spores germinate they produce protonema.

oomyctes

water mold. member of the phylum oomycota that are aquatic and reproduce by oogonia and antheridia. may form large masses of threads called mycelia.

hydrodictyon

water nets. form netlike tubular colonies with polygonal meshes. a daughter net may be asexually produced inside a parent cell and eventually released. secxual reproduction is isogamous, with two flagellated gametes forming a zygote as they unite. the zygotes become zoospores the produce large, angular cells. each new cell then becomes a new netlike colony that is released from the parent cell as it breaks down.

spirogyra

watersilk. watery sheaths, slimy. freshwater algae consisting of unbranched filaments of cylindrical cells, frequently float in masses at the surfaces of quite water. each cell contains one or more long frilly ribbon-shaped chloroplasts that look as though they had been spirally wrapped around an invisible pole (vacuole) occupying most of the cell's interior. most have one or two chloroplasts in each cell. every one of the green ribbons has pyrenoids at regular intervals down its length. does not produce zoospores. asexual reproduction occurs through fragmentation of existing filaments. fragmentation often occurs because of a storm or other disturbance. when sexual reproduction begins the individual cells of adjacent filaments form small dome-shaped bumps that fuse to form cylindrical conjugation tubes between each pair of cells. Then the protoplast of one filament flows through the conjugation tube to the adjacent cell where it fuses to that cell to form a zygote. each moving protoplast is considered a male gamete with the stationary one as a female gamete. thick walls develop around zygotes which remain dormant for some time especially during winter, eventually, each diploid zygote undergoes meiosis forming four genetically unique haploid cells, three disintegrate and one new spirogyra filament grows from the interior of the old zygote shell. sexual reproduction is called conjugation.

compression

when objects such as leaves are buried by layers of sediment, the sheer weight of the overlying material may compress them to as little as 5% of their original thickness. when this occurs all that is left is a thin film of organic material and and outline showing some surface details. virtually no preservation of cells or other internal structure take place. this is called a compression. coal is a special type of compression.

succession

when some bryophytes and lichens slowly accumulate mineral and organic material which can be used by other organisms.

phylum psilotophyta

whisk ferns. features unique to this phylum of vascular plants include sporophytes that have neither true leaves nor roots, and stems and rhizomes that fork evenly. psilotum (scientific name). consist almost entirely of dichotomously forking. usually up to 30 centimeters but sometimes up to 1 meter. enations are spirally arranged along the stems. small sporangia are fused into threes. spores released from sporangia germinate slowly in the soil. gametophytes develop spores. can be used to reduce loin cloth irritations on the skin and made a laxative liquid.

phylum chromophyta

yellow-green algae (xanthophyceae), golden-brown algae (chrysophyceae) , diatoms (bacillario phyceae), and brown algae (phaeophyceae). share several features, including food reserves, specialized pigments, and other cell characteristics. some members of the first three classes produce a unique resting cell called a statospore (they resemble a mini corked bottle complete with plugs that dissolve releasing the zoospore inside).

chromophyta

yellow-green, golden-brown, and brown algae, and diatoms.

crozier

"fiddleheads" fronds that first appear coiled at the tips and then uncoil to reveal the blades.

sargassum

Floating brown seaweed. reproduce asexually through fragmentation while some produce spores.

pseudoplasmodium

In cellular slime molds, an aggregation of amoeboid cells that forms a spore-producing fruiting body during reproduction. eventually becomes stationary and transforms into a sporangium-like mass of spores.

thalloid liverworts

best known species in genus marchantia. abt 30 cells think in center and 10 cells thick at the margin. forks dichotomously.

plants

bryophytes, ferns, cone-bearing plants, flowering plants and relatives of each of these groups.

motile

capable of spontaneous movement usually by means of flagella. many single celled organisms are called this.

pellicle

cell membrane in euglenas.

generative cell

cell of the male gametophyte of angiosperms that divides producing two sperms; also the cell of the male gametophyte of gymnosperms that divides producing a sterile cell and a spermatogenous cell.

Phylum Pinophyta

conifers these members bear distinct strobili "pine cones" and have leaves that are needlelike and arranged in clusters up to five leaves each. there are about 600 species of pines, firs, spruces, hemlocks, cedars, redwoods, and other coniferous woody plants live today. mycorrhizal fungi are associated with the roots of most conifers. can be used for emergency food, to prevent scurvy, crafting, turpentine, rosin, fuel, menthol, and dyes.

kingdom protista

consists of eukaryotes that do not fit into any of the other kingdoms. lack a set of unifying features. many consist of a singular cell but many are multicellular. single-celled usually motile and multicellular usually nonmotile. protozoans and sponges are included.

chollera

contains most of the vitamins needed for human nutrition except for vitamin c. easy to culture.

phylum cycadophyta

cycads. these slow-growing plants have the appearance of a cross between a tree fern and a palm but are not directly related to either one. the strobili of cycads are located in the center of the plant. about 300 species of cycads are known to exist many of which have been discovered within the past decade.

phylum dinophyta

dinoflagellates

ulothrix

each alga consists of a row of cylindrical cells attached end to end to form a thread called a filament, the basal cell of each filament is slightly longer than the other cells and functions as an attachment cell. contains a single chloroplast with one or more pyrenoids. any cells except the holdfast may divide and as they do so the filaments grow longer. all cells except for the holdfast may condense inside the rigid cell wall, divide by mitosis and develop into zoospores. the zoospores are quite similar to those in chlamydomonas. after swimming for a few hours they settle on objects, flagella shed and cells begin to divide. one of the two daughter cells becomes a holdfast while the other continues to divide becoming a new algal body. asexual and sexual reproduction begin the same way the contents of any cell but the holdfast condense and then divide producing swimming cells that function as gametes that then unite with gametes from other filaments to form diploid zygotes which become dormant. eventually the zygote will go through meiosis which make variable zoospores. sexual reproduction involves gametes called isogamy . zygotes are the only diploid cells other than that all cells are haploid.

euglenophyta

euglenoids

carpogonia

female sex structures on a female gametophyte thallus. consists of a cell called trichogyne.

phylum polypodiophyta

ferns. the sporophytes of ferns have megaphylls that are often large and much divided. from less than 1 cm to about 25 meters. fern leaves are megaphylls and commonly referred to as fronds. abundant in wetter tropical or temperate habitats (can be found in drier areas). sporocytes undergo meiosis in the sporangia and produce either 48-64 spores per sporangium. found staring back from 250-320 million years ago. can be used in upholstery, pillows, and mattress stuffing. can be used as human food but is mildly poisonous to livestock. has been used for many medicinal purposes.

odeogonium

filamentous green alga, often found attached to aquatic plants and algae. strictly epiphytic and in no way parasitic. the basal cells of unbranched filaments form holdfasts and the terminal cell of each filament is rounded. the remaining cells are cylindrical and attached end to end. bulging female reproductive cells. each cell contains a netlike chloroplast that forms a tube something like a loosely woven basket, there are pyrenoids throughout the net. can reproduce asexually either by zoospore or fragmentation. the tip of each filament may produce a zoospore (swimming haploid spore) that eventually settle and divide to form new filaments. short, boxlike cells carry male gametes (sperm cells) these resemble zoospores but are smaller. certain other cells carry large female gametes (egg cells). each specialized cell carries either two male gametes or one female gamete. the sperm cells swim to egg cells attracted by chemicals released by the eggs. one sperm unites with the egg forming a zygote after fertilization the zygote wall thickens and reddish oil accumulates in the protoplasm. zygotes may remain dormant for a year or more but eventually undergo meiosis producing four haploid zoospores each capable of developing into a new filament. the sexual reproduction exhibited in which one gamete is motile while the other gamete is larger and stationery is called oogamy.

phylum anthocerophyta

hornworts. gametophytes may resemble those of liverworts sometimes with a crumpled appearance and after fertilization the sporophyte resembles a hornlike structure that projects out of the gametophyte. normally less than two centimeters. thalli have pores and cavities filled with mucilage. nitrogen fixing cyanobacteria often grows in the mucilage. rhizoids anchor the plant. asexual reproduction: fragmentation or as lobes separate from the main part of the thallus. a few hornworts form tiny tubers that are capable of becoming new gametophytes sexual reproduction: archegonia and antheridia are produced in rows just beneath gametophytes. some species have unisexual plants. sporophytes have numerous stomata. they have no setae (stalks) sporophyte undergo meiosis and produce spores.

phylum equisetophyta

horsetails and scouring rushes. the sporophytes of these plants have ribbed stems containing silica deposits and whorled scalelike microphylls that lack chlorophyll. deposits of silica accumulate on the inside wall of the epidermal cells of the stems. usually less than 1.3 meters tall but some more than 4.6 meters tall. normally in whorls at jointed stems. both branched and unbranched species have leaves in whorls at the nodes. most photosynthesis occurs in the stems. stems are ribbed and have obvious nodes and internodes, numerous stomata between the grooves in the ribs. have water-conducting carnial canals. have vallecular canals that contain air. aerial stems develop from horizontal rhizomes. in some species the rhizomes have adventitious roots. reproduction can happen by fragmentation but usually due to sexual reproduction. germination of spores usually occurs within a week of their release. carboniferous period. they have been known to be eaten or drinking from, increase urine flow they can also be burned to use the ash to alleviate sore mouths and severe burns

the fossil record

indicated that less than 1 billion years ago all life was confined to the ocean (because they were protected from dehydration, ultra violet radiation, and large fluctuations in temperature. they also absorbed the nutrients they needed directly from the water.) suggests that beginning about 400 billion years ago green algae began to make the transition from water to land.

cladophora

is a branched, filamentous green alga whose species are both represented in both fresh and marine waters. cells are mostly multinucleate.

domain eukarya

kingdoms: protista, plantae, fungi, and animalia.

antheridium

male gametangium.

pollen cone

male strobilus that produces microsporangia.

brown algae (phaeophyceae)

many are assigned to the class phaeophyceae, previously they had been in phaeophyta. relatively large and none are unicellular or colonial. only a few reside in freshwater most reside in colder ocean waters usually in shallower areas. many have a thallus that is differentiated into a hold fast, a stipe, and flattened leaflike blades. main food reserve is laminarin.

algae

may have flattened leaf-like blades but have no true leaves or flowers.

club mosses

member of the genus lycopodium with structure resembling mosses and reproducing by spores. spores produced flash powder for cameras. two major genera are lycopodium and selaginella.

green algae

members of the phylum chlorophyta characterized among other things as having both chlorophylls a and b. in phylum chlorophyta. store their food in the form of starch within chloroplasts. most have a single nucleus in each cell a reproduce both sexually and asexually.

acetabularia

mermaids wine glass. sexual reproduction is isogamous. a marine alga consisting of a single huge cell shaped-like a delicate mushroom.

phylum bryophyta

mosses. gametophytes vary but can have stemlike and leaflike structures that make them distinguishable from liverworts and hornworts. sporophytes produced after fertilization often tower above the gametophyte generation and release spores from unique sporangia. leaves have no mesophyll tissue, stomata or veins. never lobed, or divided, nor do they have a petiole. sexual reproduction: formation of multicellular gametangia at apices. both male and female gametangia are normally produced on the same plant. archegonia somewhat cylindrical. a single egg is produced. several archegonia are normally produced at the same time. male gametangia are hot dogs shaped or roundish with walls that are one cell thick. asexual reproduction: can reproduce asexually through fragmentation

golden-brown algae (chrysophyceae)

most are freshwater plankton and produce yellow-brown carotenoid pigments. the motile cells have two flagella of unequal length inserted at right angles to each other, with a photoreceptor on the short flagellum. the photoreceptor is usually a shaded eyespot at the flagellar end of a large chloroplast. silica scales are present in some species.

yellow-green algae (xanthophyceae)

mostly freshwater organisms with a few marine and terrestrial organisms. two flagella of motile cells are oriented in opposite directions. brownish pigment fucoxanthin is not present except in vaucheria, an oogamous, coenocytic, filamentous species. nonmotile spores are commonly formed during asexual reproduction less frequently zoospores are produced. sexual reproduction is relatively rare but when it occurs it may exhibit specialization with oogonia and antheridia being formed on special branches.

diatoms (bacillariophyceae)

mostly unicellular algae in fresh and saltwater. abundant in colder marine habitats. some can withstand extreme drought. look like tiny ornate boxes with lids, many look circular from the top. as much as 95% of the wall content is silica. walls have fine pores and grooves that are passageways connecting the protoplasm to the watery environment outside of the shell. many have one, two, or many chloroplasts per cell. they have chlorophyll a, chlorophyll c1, and chlorophyll c2. chloroplasts are usually brown because of the fucoxanthin. food reserves are oils, fats, or the carbohydrate laminarin. freshwater diatoms that have a lengthwise groove called raphe glide backward and forward in jerky motions at a rate of up to three times their length in 5 seconds. it is believed that movements occur in response to external stimuli such as light. when they reproduce half of the cells become progressively smaller through several generations until through sexual reproduction the original cell size in restored. before any cell division can occur an adequate source of silicon must be present in the surrounding medium. division in culture is rhythmic all cells divide at the same time. after a diatoms cell contents, which are diploid, have undergone mitosis and division the two halves of the cell separate with a daughter nucleus remaining in each half, a new half-wall fitting inside the old half is formed. eventually, the ration of cytoplasm to nucleoplasm reaches a critical point and a cell undergoes meiosis and produces four gametes that escape. these then fuse with other gametes, becoming zygotes called auxospores. up to 40% of a diatom's mass is oils that are rich sources of vitamins for humans.

haptophyte

mostly unicellular with two smooth flagella of similar length inserted at the apex. have a haptonema. two disk-shaped chloroplasts in each cell. salt and freshwater.

red algae

occur in warmer and deeper waters. a few are unicellular but most a filamentous. relatively complex life cycles including three types of thallus. meiosis usually occurs on a thallus called tetrasporophyte while gametes are produced on separate male and female thalli. all reproductive cells are nonmotile. zygotes might migrate from one cell to another through special tubes

dinoflagellates

often cause bioluminescence. produce a flash of blue light for one tenth of a second.

enation

one of the tiny, green leaflike outgrowths on the stems of whisk ferns (psilotum).

lycopodium (ground pines)

sometimes called ground pines. stems of ground pine sporophytes are simple or branched. mostly less than 30 centimeters but sometimes up to 1.5 meters. stems develop from branching rhizomes. leaves may be whorled or in a tight spiral. adventitious roots, whos epidermal cells often produce root hairs, develop along the rhizomes. produce sporangia on short stalks in the axils of specialized leaves. in the sporangia, sporocytes undergo meiosis producing spores that are released and carried away by air currents. after germination independent gametophytes develop from the spores. the gametophyte body usually develops in the ground in association with mycorrhizal fungi, some develop on the surface though. because sperm are flagellated water is essential for fertilization to occur. zygotes first become embryos then develop into mature sporophytes. if the sporophyte is underground chlorophyll does not develop until it emerges into the light. several sporophytes may be produced from a single gametophyte.

conceptacles

spherical hollow chambers.

gametophores

stalk-like structures that support the gametangia.

paraphyses

sterile hairlike multicellular filaments.

ovule

structure in seed plants in which the female gametophyte develops.

alternation of generations

the alternation between the haploid gametophyte and the diploid sporophyte phase in the life cycle of sexually reproducing organisms.

foot

the basal part of the embryo of bryophytes and other plants; it is attached to and absorbs food from the gametophyte.

blades

the conspicous flattened part of a leaf.

oogonia

the female sex organ of certain algae and fungi, typically a rounded cell or sac containing one or more oospheres.

coprolites

the fossilized dung of prehistoric animals and humans. may contain clues to past feeding habits.

prothallus (singular: prothalli)

the gametophyte of ferns and their relatives. also called prothallium. only one cell thick.

imprint

the image of a compression like the details of a foot or hand pressed into cement is called an imprint.

operculum

the lid or cap that protects the peristome of a moss sporangium

antheridia

the male gametangium of certain algae, fungi, bryophytes, and vascular plants other than gymnosperms and angiosperms.

spermtangia

the male sex structures.

red tide

the marine phenomenon that results in water becoming temporarily tinged with red due to the sudden proliferation of certain dinoflagellates that produces substances poisonous to animal life and human life.

archegonia

the multicellular female gametangium of bryophytes and most vascular plants other than angiosperms.

plasmodium

the multinucleate, semiviscous liquid, active form of slime mold. it moves in a crawling flowing motion. has no cell walls.

seed coat

the outer boundary of a seed, it is developed from the integument.

integument

the outermost layer of an ovule; usually develops into a seed coat. a gymnosperm ovule usually has a single integument, and an angiosperm ovule usually has two integuments.

heterospory

the production of both microspores and megaspores.

bioluminescence

the production of light by living things. at times carried out by algae called dinoflagellates. a defense response.

venter

the site of the egg in the enlarged basal portion of an archegonium.

indusia

the small membranous sometimes umbrella like covering of a developing fern sorus.

seta

the stalk of a bryophyte sporophyte.

stipe

the supporting stalk of seaweeds, mushrooms, and certain other stationary organisms.

ligule

the tiny, tongue-like appendage at the base of a spike moss or quillwort leaf.

haptonema

third flagellum that does not function in propulsion but instead has a sticky tip that aids in capturing food.

coleochaete

tiny, freshwater, green alga that grows as an epiphyte on the stems and leaves of submerged plants.

calyptra

tissue from the enlarged archegonial wall of many mosses that forms a partial or complete cap over the capsule.

dinoflagellates

two flagella that are distinctly arranged. contain xanthophyll pigments, chlorophylls a and c2. fresh and saltwater.

petrification

uncompressed rocklike materials in which the original cell structure has been preserved. about 20 different mineral substances are known to bring about petrification. can be studied by cutting thin sections with a diamond saw, then examined through a compound microscope.

contractile vacuoles

vacuoles near the base of the flagella that contract and expand. they may regulate the water content of the cell and remove waste products.