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92 Cards in this Set
- Front
- Back
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Plant kingdom
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Algae - 20,000 species
Bryophytes - 25,000 Ferns 10,000 Fern allies - 1,000 Gymnosperms 1,000 Angiosperms 235,000 |
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Flowering Plants
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Most abundant group of plants on earth
Adapted to mesic, xeric and hydric habitats Exhibit extreme diversity in form and growth habit (trees, shrubs, herbs, vines, aquatic plants) One of two groups of extant group of seed plants, extant = opposite of extinct |
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Seed Plants
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The most highly specialized plants are seed plants
Two groups of seed plants are recognized as: Gymnosperms - (cone-bearing) Angiosperms (flowering plants) |
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Gymnosperms (naked seeds)
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Seeds borne uncovered on the surface of the cone scales
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Angiosperms (enclosed seeds)
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Seeds completely enclosed within a protective structure, the fruit
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Characteristics of angiosperms
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Specialized reproductive structures called flowers
Ovules enclosed in an ovary that develops into a fruit Double fertilization Endosperm development Exploitation of animals as pollinators |
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Sexual Reproduction
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Most plants and animals have life cycles that involve the process of sexual reproduction
Sexual reproduction = any reproductive process that involves the fusion of male and female gametes to form a zygote. Look at the sexual reproduction process and mitosis |
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Life cycles of Eukaryotic organisms
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Exhibit one of three different types of life cycles
Gametic life cycle Zygotic life cycle Sporic life cycle |
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Gametic life cycle
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Characteristic of all animals and some algae
Meiosis occurs during the production of the gametes Gametes are the only haploid stage of the life cycle Know all the pieces of the life cycle |
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Sporic life cycle (most plants)
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Characteristic of land plants and some algae
Meiosis results in the production of haploid spores Gametes are produced by mitotic cell divisions Two distinct phases of the life cycle exist, one haploid and one diploid The two phases alternate with one another in the life cycle LOOK AT THE SPORIC LIFE CYCLE DIAGRAM Diploid is the sporophyte |
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Plant life cycle
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All land plants exist in two distinct forms (or generations) during their life cycle:
Spore producing generation Gamete producing generation There two generations alternate with one another in the life cycle (alternation of generations) The spore producing phase of the plant life cycle is called the sporophyte generation Cells of the sporophyte are diploid and undergoes meiosis to produce haploid spores The gamete producing phase of the plant life cycle is called the gametophyte generation Cells of the gametophyte are haploid (produces sperm and egg cells) Gametes are produced my MITOSIS 00 Angiosperms |
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The Flower
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A reproductive structure whose parts are believed to have evolved from highly modified leaves
The floral parts are attached at the end of a stalk called the pedicel Typical flower has 4 sets of parts: sepals, petals, stamen (pollen producing), pistils (ovary or egg) |
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Floral Structure
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Sepals -
outermost set of floral parts usually small green leaf likeprotect flower in bud Petals - usually large, showy, colorful Attract pollinators Stamens Consist of filament and anthers Anthers contain sporangia producing spores that develop into male gametophytes Pollen = male gametophytes, contain sperm cells Pistils -Consist of an ovary, style and stigma Ovary contains sporangia which produce spores that develop into female gametophytes |
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Life cycle of angiosperms
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Sporophyte is the dominant generation of the life cycle in flowering plants
Sporangia are produced by a specialized reproductive structure, the flower Two different kinds of sporangia occur, each producing a different kind of spore Stamens of the flower contain what are called microsporangia where meiosis occurs and a large number of tiny microspores are produced Each microspore develops into a male gametophyte (pollen grain) that contains sperm cells |
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Stamen Structure
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Each stamen bears two anthers that contain microsporangia
Meiosis occurs and produces numerous microspores Chambers are the mircrosporangia (diploid) where meiosis occurs and haploid microspores are produced and each of the microspores are surrounded by a cell wall once produced the microspores divide through mitosis and develop into a gametophyte, only the cell divides, the cell wall remains intact then another mitotic division occurs and only happens to the generative cell and three cells are produced and called a mature male gametophyte ( a tube cell and 2 sperm cells) also called a pollen grain One cell is a tube cell and the other is a generative cell |
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In angiosperms this is a two step process
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Pollination is the first step
Double fertilization |
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Pollination is the first step
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Pollen = transfer of pollen grains from the anther of one flower to the stigma of another, this is usually carried out by animals or sometimes wind
Second step is Pollen grains produce a long hollow tube-like structure that grows down through the tissue of the pistil towards the ovule |
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Double fertilization
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At the micro Pyle, the tip of the pollen tube dissolves and the two sperm cells are released
One sperm fuses with egg cell to form a diploid zygote Second sperm fuses with the two central nuclei to form a single triploid cell. Process is termed double fertilization |
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Post fertilization Events
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Zygote develops into an embryonic sporophyte
Triploid cell develops into a specialized nutritive tissue called endosperm Integuments harden and thicken and develop into a seed coat (seed coat =mature ovule) Ovary wall enlarges and thickens and develops into a fruit Each seed contains an embryonic sporophyte surrounded by a tissue called endosperm that is filled with stored Fruits are the mature ovaries |
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Evolution
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The process by which organisms change through time as a result of adaptation to their enviroments
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Coevolution
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Process by which two groups of organisms influence each others evolution
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Coevolution between plants and animals
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Flowering plants have evolved relationships with animals to help them with: protections reproduction dispersal
Usually (not always) these relationships benefit both plant and the animal |
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The Ant Acaia
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Ants live in the large hollow spines of the acacia
The plants produce nectar and food bodies to feed the ants The ants protect the acacia from other plants |
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Rewards of Coevolution
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In most co evolutionary relationships , the plant provides a reward in return for the animals service
The most common reward is food |
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Flowering plants and Animals
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The most common examples of coevolution between flowering plants and animals deals with:
Pollination Dispersal |
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Pollination
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Gymnosperms: pollen transported by wind currents
Angiosperms: Pollen is usually transported by animals, occasionally by wind |
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Gymnosperms Pollination
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Most gymnosperms are wind pollinated (some cycads are pollinated by insects)
Not efficient Requires large populations sizes to be effective Energetically expensive (requires large numbers of pollens grains) |
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Angiosperms Pollination
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Much more efficient
Large population sizes not required Smaller amounts of energetically expensive pollen is required Important factor in understanding the evolutionary success of flowering plants |
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Function of the flower
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The function of a flower is to secure the successful fertilization of its ovules by the sperm cells in pollen grains that come from other flowers of the same species
A flower should: Promote out crossing Attract pollinators Align pollinators to come in contact with the reproductive parts of the flower Protect ovules from herbivorous insects |
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Cross Vs. Self-pollination
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Cross pollination
Also called out crossing Involves two different individuals (two flowers on two separate plants Self pollination Also called inbreeding Involves one individual (one flower or two flowers on the same plant |
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Cross Pollination
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Outcrossing is preferable to inbreeding
Crossing between individuals increases genetic variability of a populations Genetic variability enabels a population to better adapt to a changing environmental conditions Genetic variability is the raw material of evolution |
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Barriers to self pollination
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Spatial separation
Temporal separation Heterostyly Self-incompatibility |
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Spatial separation
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of stamens and pistils (dioecism; stamens and pistils borne on separate plants)
Ex. Ilex (hollies) only half the plants produce berries because of staminate and pistillate flowers are on separate plants |
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Temporal separation
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flowers are perfect but the stamens and pistils do not mature at the same time
2 types of temporal Protandry - anthers mature and release pollens before the stigma is receptive Protogyny - stigmas receptive before the anthers dehisce and release pollens Protandry - digitalis produces elongate racemes or portentous flowers |
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2 types of temporal
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Protandry - anthers mature and release pollens before the stigma is receptive
Protogyny - stigmas receptive before the anthers dehisce and release pollens Protandry - digitalis produces elongate racemes or portentous flowers |
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Protandry -
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anthers mature and release pollens before the stigma is receptive
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Protogyny -
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stigmas receptive before the anthers dehisce and release pollens
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Heterostyly
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A modification of flower structure that help prevents self pollination
Defined- the production of 2 different kinds of perfect flowers in a single population with the stamens and stigmas located at different levels Ex. Primrose |
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Self-incompatibility
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Most common method of preventing inbreeding .
In most flowering plants, the stigma has an inhibitory effect on genetically identical pollen grains Pollen grains may not germinate or pollen tubes may not grow properly |
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affable (adj.)
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friendly, amiable
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Floral Color
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Produced by pigments and other means
Blues, purples, reds, and pinks are produced by anthocyanin pigments Yellows are produced by anthoxanthins Oranges are produced by carotenoids Green is produces by chlorophyll White is produced by air pockets in intercellular spaces Flowers come in different colors because different pollinators have different color preferences Bees prefer flowers that are blue and yellow Birds prefer red and yellow Moths prefer white and other light colors flowers |
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Floral fragrances
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Fragrance is characteristic of many flowers
Fragrance molecules are not produced for our benefit, but to attract pollinators Different pollinators are attracted to different fragrances Beetles prefer spicy and fruity scents Butterflies and moths prefer sweet scents Bees prefer sweet or mint fragrances Flies prefer putrid smells Hummingbirds have a poorly developed olfactory sense and are not attracted to fragrances |
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Rewards
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Animals do not provide their carrying services free of charge
Floral colors and fragrances are signals that advertise the predator Rewards include Nectar Pollen Food bodies |
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Nectar
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Principle reward in most flowers
Usually produced by specialized nectar gland or specialized groups of nectar producing cells in flowers Principle ingredients include glucose, fructose, sucrose, amino acids and other compounds |
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Nectar glands
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Can bee seen in many flowers
Usually located near the base of the ovary or corolla |
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Nectar productions
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Most flowers maintain a delicate balance between the amount of nectar produced and needs of the pollinator
Too much - pollinator may be satisfied after visiting only one flower Too little - may not be worthwhile for pollinator to visit flowers at all |
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Nectar Guides
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Petals often bear lines or rows of dots that converge on the nectar source
Nectar guides à help direct the pollinator to the reward while causing it to come into contact with the stamens and stigmas Guides are common in flowers pollinated by bees and other day flying insects |
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Pollen
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Pollen plays two roles in floral biology:
Male gametophyte that produces sperm cells for sexual reproduction Reward for pollinators in some species Pollen is nutritious and is used as a reward by some plants Most pollen contains sugars, starch, proteins, free amino acids, oil droplets, minerals and vitamins Has a high food value Cacti, poppies, and mimosoid legumes are all insect pollinated but produce large quantities of pollen |
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Food bodies
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Least common of rewards offered
Some plants produce oil rich food bodies that are offered as a reward to insects with chewing mouth parts As insect feeds on the food bodies it contacts the reproductive parts of the flower Ex. Clianthus (Carolina allspice) |
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Floral constancy
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The association of floral characteristics with the presence of a reward leads to the development of floral constancy
Floral constancy = the loyalty of a pollinator displays to the flowers of a single plant species It’s a learned behavior that benefit’s the plants and animal Benefit to the plant: pollen is not wasted on flowers of other species Benefit to the animal: increased feeding efficiency from concentrating on a single kind flower |
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Pollination syndromes
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Sets of characteristics that adapt a flower to pollination by a specific agent are termed pollination syndromes
The pollinator of a flower can often be identified by looking at the features of the flower |
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Beetle Pollination
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Beetles are primitive insects with chewing mouthparts and poor vision but with a well developed sense of smell
A large number of beetle pollinated species are found among the most primitive flower plants |
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Characteristics of Beetle pollinated flowers
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Not showy, usually pale or brownish in color
Fragrance is usually fruity or spicy Ex. Magnolia or Carolina allspice Reward is pollen or food bodies Ovules well protected (ovary inferior or plant containing toxic alkaloids) |
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Bee Pollination
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Bees, butterflies, moths and flies are more advanced insects groups than beetles
Flowers are pollinated by these insects are more highly advanced than the beetle pollinated flowers Bees are highly evolved insects with well developed sense of vision and smell |
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Bee Flowers
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Flowers are usually blue, yellow, purple, white or pink (not red)
Lower petals enlarged to forma a landing platform (makes flowers zygomorphic) Nectar guides present on petals Nectar is the principle reward Fragrance is sweet or minty Petals are often fused to form a short wide tube |
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Butterfly Pollination
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Butterflies also have well developed senses of vision and smell
Have a much longer tubular mouthparts |
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Butterfly Flowers
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Flowers come in a wide variety of colors including red
Fragrance is sweet Nectar is the reward Flowers with slender tubular shape to accommodate butterfly mouthparts Landing platform may be provided by either the flower or the inflorescence |
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Moth Pollination
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Flowers similar in size and color to butterfly pollinated flowers
Differences reflect the differences in behavior Usually white or light colored Flowers are open at night Fragrance and nectar are produced at night Flowers are held away form the foliage Yucca plant is a good example and honey suckle No landing platform |
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Pollination of Yucca
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Yucca plants are pollinated by small moths in the genus Tegeticula (commonly called yucca moths)
Female moth collects pollen from a flower, rolls it into a ball, then flies off to another yucca and checks the scent for other moths and if a female was there then she keeps going until she finds one without the scent of a female. Then she pierces the ovary wall and lays eggs among the ovules Then deposits pollen on the stigma of that flower Moth larvae feed on developing seeds, but only consume about 20 percent When mature the larvae chew through ovary wall and fall to the ground and pupate |
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Moth and Butterflies
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Butterflies are diurnal insects that land on the flower when feeding
Moths are nocturnal or crepuscular insects that hover in front of the flower when feeding |
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Fly Pollinated Flowers
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Usually reddish or brownish in color
Smell terrible, often like rotting flesh Sometimes called “carrion flowers” |
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Pollination of Figs
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Commonly cultivated species include Ficus Carica (north America) and Ficus sycomorus
Flowers borne in a specialized hollow inflorescence termed a syconium Each syconium contains staminate flowers and 2 types of pistallate flowers |
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Fig Gall Wasp Life Cycle
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Female wasp enters syconium through ostiolum when pistillate flowers are mature
Deposits one egg in the ovary of only the short styled flowers Pollen on her body rubs onto stigmas of both types of flowers Only long styled flowers develop seeds Short styled flowers develop into small galls Egg begins to hatch in a few days and male wasps emerge Males are blind and wingless but have strong jaws |
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Fig Gall Wasp Life Cycle 2
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Males begin to search for un-hatched galls, finding one they gnaw a hole in the side, insert the tip of abdomen and fertilize the female
Males then gather near ostiolum and chew a tunnel through the syconium wall When tunnel is completed the male dies Females hatch a couple hours later, each has well developed eyes and wings Crawling through the interior of the fig they pick up pollen from the mature staminate flowers Females exit through the tunnel and visit another fig |
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BIRD POLLINATED FLOWERS
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· More common in tropical regions than in temperate areas (more species of nectar feeding birds occur in the tropics)
· Hummingbirds are the only nectar feeding birds in North America · Flowers usually large and sturdy to withstand visits from a large pollinator · Red or orange in color, often marked with yellow · Large amounts of nectar produced (birds need a larger reward than insects) · Feeders usually red with yellow flowers · No fragrance to hummingbird pollinated flowers (hummingbirds and other birds have poor sense of smell) · Flowers held away from foliage o Ex. Trumpet creeper vine |
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BAT POLLINATION
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· More common in tropical regions
· In North America only a few plants are bat pollinated o Ex. Century plants (agane spp.) o Saguaro cactus (caregiea gigontea) o Orgon pipe cactus (Lemaireocerus thurbeis) · Flowers usually large and sturdy to withstand visits from large pollinators · Light colored (white or yellow) · Flowers held away from foliage · Nectar and fragrance produced at night |
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POLLINATION WITHOUT ANIMALS
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· Not all flowering plants are dependent on animals to transport pollen grains
· Some species use other strategies to ensure that pollination occurs · Two common alternative strategies are the production of cleistogamous flowers and wind pollination (abiotic pollination) |
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CLEISTOGAMOUS FLOWERS
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· Produce functional stamens and pistils
· Flower never opens so cross pollination can not occur · Cleisto means “hidden” gamous = sexual reproduction · Produce seeds as a result of self pollination · Cleistogamous flowers appear to be a sort of “back-up” system in some plants · Plants that produce cleistogamous flowers also produce normal chamogamous flowers (open bud flowers) · If cross pollination does not occur, the plant will still produce some seed · Plants that frequently produce cleistogamous flowers include: o Violets o Wood sornels o Henbit |
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WIND POLLINATION
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Also known as anemophily
· Entomophily – insect pollination · Contharophily – beetle pollination · Melittophily – bee pollination · Psychophily – butterfly pollination · Phalaenophily – moth pollination · Myophily – fly pollination · Myrmecophily – ant pollination · Ornithophily – bird pollination Chiroplerophily – bat pollination · Anemophily – wind pollination |
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Wind pollinated angiosperms all share a number of characteristics in common
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· Usually form large communities with many individuals of a style species (prairie grass, oak-hickory forest)
· Flowers small, greenish or brownish, and often appear before the leaves · Petals absent · Fragrance absent · Nectar and other rewards absent · Flowers usually imperfect, the plants often dioecious · Stamens often have greatly elongate filaments · Abundant pollen produced |
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Wind pollinated
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species are spread all over the classification system and are not closely related
· Most primitive flowering plants are beetle pollinated · Anemophily is not a primitive characteristic among angiosperms but has apparently evolved more than once |
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Wind and Animal pollinated
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species usually produce 400-800 pollen grains per ovule
· Animal pollinated species usually produce 10-100 pollen grains per ovule · Pollen grains small and smooth walled (wind carried pollen much smaller and smooth walled) · Styles/ stigmas often plumose (feathery) · Among angiosperms, anemophily is considered to be an advanced characteristic · Wind pollinated flowering plants believed to have evolved from animal pollinated ancestors |
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WHY ANEMOPHILY?
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· Several situations where animal pollination might not be efficient:
o When pollinators aren’t available o When the environment keeps pollinators from operating efficiently |
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Distribution of wind pollinated angiosperms in Europe
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o Central Europe 10%
o Coastal Islands 50% o Arctic regions 40% |
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· The willow genus (Salix)
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is widely distributed from temperate regions to the arctic
o All temperate species of willow are insect pollinated o Arctic species are wind pollinated · Tropical regions are characterized by dense forests o Few air currents are present o A tremendous number of potential animal pollinators are available over 95% of plant species are animal pollinated |
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Dispersal
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Pollination is an important aspect of the life cycle of flowering plants
The evolution of most angiosperms is closely linked to that of their animal pollinators Many biologist argue that the evolution of dispersal mechanisms has been equally important |
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Dispersal mechanisms -
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adaptations that promote the spread of a species into a new species
May involve: seeds, fruits, and specialized vegetative structures Efficient dispersal mechanisms benefit a plant in two ways 1. Reducing competition between parent and offspring 2. Allowing for colonization of new areas |
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Wind dispersal
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Tumbleweeds - Whole pant, or a portion, breaks off and is blown by the wind, scattering seeds
Plants are always herbaceous, usually annuals Ex. Russian thistle |
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Winged fruits
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Wings usually develop form persistent bracts or perianth parts or as an outgrowth
Commonly produced by trees and shrubs Usually produces in capsules that dehisce to release the seeds Wings develop as an outgrowth of the seed coat |
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Plumed fruits
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Feathery appendages develop from the pappus in many Asteraceae or from persistent styles
A tuft of silky hairs (coma) may develop at the end of the seed Many Milkweeds and members A coma is an apical tuft of hairs that aids in wind dispersal |
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Water Dispersal
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The seeds and or fruits of many riparian species have corky waterproof walls are transported by water currents
Coconuts and sea beans may be carried thousand of miles by ocean currents and have thick walls resistant to germination in salt water |
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Ingestion of seeds and fruits
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Birds and mammals eat the fruits of many species
Virtually all fleshy fruits are adaptations for animal dispersal Seeds pass through digestive tract unharmed and are deposited somewhere else |
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Elaiosomes
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- Lipid rich food bodies attached to seeds
They are usually dispersed by ants that carry the seeds back to their nests Ant colony feeds on the oil and discards the seeds outside the nest |
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Adhesion to fur and feathers
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Many seeds and fruits develop spines, prickles, hairs or sticky coverings designed to adhere to animals
The genus Proboscidea (devils claw) has unusual fruits that are modified for dispersal by large hoofed mammals |
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Transport in mud
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Many species of aquatic and wetland plants have small seeds that are probably transported in mud attached to fur or feathers
Darwin suggested this method |
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Elastic dehiscence
Mechanical Dispersal |
Elastic dehiscence
In species Geranium and Erodium the elongate styles separate into five curled slings Seeds may be flicked a meter or more from the plant |
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Explosive Dehiscence
Mechanical Dispersal |
In some species the mature fruit explodes and ejects the seeds a considerable distances
Wood sorrel commonly pop at dispersal |
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Fruit of the squirting cucumber
Mechanical Dispersal |
is an oblong berry about 6cm in length
Turgor pressure builds up inside mature fruit causing pedicel to become detached Fruit wall contracts suddenly and soft tissue inside fruit, including the seeds is squirted out |
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The diversity of angiosperms
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235000 flowering species named
Total number may reach 1 million The coevolution of angiosperms and different animal groups explains much of this diversity |
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WIND POLLINATION
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o Grasses sedges
o Nettles oaks o Elms hickories · Wind pollinated species are spread all over the classification system and are not closely related · Most primitive flowering plants are beetle pollinated · Anemophily is not a primitive characteristic among angiosperms but has apparently evolved more than once |
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Pistil
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of the flower contains mega sporangia where meiosis occurs and a small number of large megaspores are produced.
Each megaspore develops into a female gametophyte (female egg) Ovules Each ovule consist of a single mega sporangium that is surrounded by layers of protective tissue called integuments. Meiosis occurs in the mega sporangium and produces megaspores. One megaspore in each ovule will develop into a female gametophyte containing an egg cell. |
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Pistil 2
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Ovary is surrounded by ovary wall and there are one or more chambers that contain ovules, the ovule consist of a mega sporangium and is surrounded by one or two layers of integuments that is open at one end (micro Pyle) , and each ovule is connected to the ovary wall by a finiculus. The mega sporangium has meiosis occur in each one and the end result is 4 haploid megaspores. 3 of the megaspores degenerate and the nutrients is absorbed by the remaining megaspore and is the functional megaspore, the megaspore will go through 3 successive mitotic divisions and form a female gametophyte that have 8 daughter cells that have a definite orientation, the egg cell, on either side of the egg cell are two cells called synergids and at the opposite side is the 3 antipodal cells and the 2 central cells are called “central cells or central nuclei”
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