Botany: Seed Plants - Angiosperms
I. Angiosperm - means “_________________________________________________” A. The “vessel” is the ______________________. 1. 1. Many flowers have _______________ which are composed of a single to multiple united carpels. 2. The carpel is like an inrolled leaf with seeds along its margins. 3. A carpel consists of 3 parts… a. The _______________ – swollen basal portion containing the ovule 1) The ovule becomes the seed after fertilization b. The _______________ – neck of the pistil which holds up the stigma c. The _______________ – swollen tip of pistil upon which the pollen falls
Image modified from: http://www.auburn.edu/academic/classes/biol/1030/bowling/lecturenotes/topic7_files/image004.jpg B. The angiosperms are the flowering seed plants. 1. They all belong to Phylum (Division) ________________________________ (formerly Anthophyta) 2. Most likely evolved from “seed ferns” or ______________________. 3. The flower is probably a modified ______________________ with petals being modified ______________________. C. In the fossil record, the angiosperms appear the most recently (they are the youngest of the plant types we have studied). 1. They are also the most complex of the plants in terms of their reproduction. II. Characteristics of all Angiosperms A. Ovary characteristics: 1. Ovary type- simple or compound (based upon the number of carpels) a. ______________________ ovaries have one carpel b. ______________________ ovaries have multiple carpels 2. Ovary position-
a. inferior (petals and anthers attached above the ovary) b. half-inferior (petals and anthers attached around middle of ovary) c. superior (petals and anthers attached below the ovary) B. Flower Characteristics 1. Complete vs. incomplete flowers a. ______________________ flowers have sepals, petals, stamens, and carpels. b. A flower lacking any of these whorls is called ______________________. 2. Flower symmetry a. ______________________________ flowers have Radial flowers (can be divided into symmetrical halves in any plane) 1) This is the type of symmetry we see in wagon wheels. 2) e.g. b. ______________________ flowers have bilateral (2-sided) symmetry 1) This is the type of symmetry humans have (can be divided into left & right symmetrical halves in only one plane) 2) e.g.
Images modified from: http://www.caringfororchids.net/wp-content/uploads/2009/08/orchid-anatomy.jpg and http://content.answers.com/main/content/img/Gardeners/f0005.jpg 3. Sexuality a. Perfect vs. imperfect flowers
Images modified from: http://nzdl.sadl.uleth.ca/gsdl/collect/hdl/index/assoc/HASH0167.dir/p064.png and http://extension.oregonstate.edu/mg/botany/images/fig20.gif 1) A perfect flower has both ______________________ and ______________________ present. a) This flower is ______________________ & technically capable of ______________________. b) Typical flowers are bisexual. 2) An imperfect flower has either pistils (& is ______________________) or stamens (& is ______________________), but not both. a) This flower is unisexual & incapable of self- pollination. b) If only pistils are present the flower is said to be ______________________. c) With stamens only, ______________________. b. _____________________________ (“one house”) vs. _____________________________ (“two houses”) plants 1) Monoecious plants are technically capable of self- fertilization. This can occur one of two ways… a) b) c) Few plants intentionally self-fertilize. There are mechanisms in flower structure (e.g. anthers below pistils) and in bloom timing (i.e. male & female flowers bloom at different times) to prevent self- fertilization. 2) Dioecious plants are never capable of self-fertilization. a) These plants actually are male & produce staminate flower only, or b) They are female & produce pistillate flowers only. c) e.g. d) The benefits of being dioecious is that it ensures __________________________________, not self- fertilization. This greatly increases the genetic ______________________ of the species. e) The cost of sexual fertilization is that if the species becomes rare & endangered, there may be no opportunity to fertilize eggs & produce seeds. III. The angiosperms are divided into 2 classes; the monocots & dicots. A. Class __________________________________ (formerly Dicotyledonae) 1. e.g. just about anything you buy in the produce section of the grocery store except corn, pineapples, onions, and sugar cane. B. Class __________________________________ (formerly Monocotyledonae) 1. e.g. Corn, grain crops, bamboo, grasses
**Be SURE to review the diagram of the life cycle of a typical flowering plant below!**
IV. Gametophyte Development A. Female Gametophyte Development
1. A ______________________________________________________ differentiates from other cells in the ovule while the flower is still developing in the bud. a. After meiosis, four __________________________________ are produced; three of which degenerate. 2. The nucleus of the remaining megaspore undergoes three divisions, resulting in 8 haploid nuclei within a single cell (_________________________________________________). 3. At the same time, the outer layers of the ovule become differentiated into ____________________________________________. a. The integuments later become the _______________________. b. As the integuments develop, a ______________________ is left as an opening at one end. 4. The nuclei migrate to the poles of the cell with four at each end. 5. One nucleus from each group migrates toward the middle of the cell (____________________________________________). a. The polar nuclei may fuse or may remain separate until fertilization occurs. 6. ____________________________ form around the remaining nuclei. 7. In the group closest to the micropyle, one cell functions as the ______________________. a. The other two cells, called ______________________ either degenerate or are later destroyed as the tissues enlarge. 8. The three cells at the other end, called ______________________, serve no purpose and degenerate. 9. At this point, the female gametophyte is called the ____________________________________________. Images modified from: http://www.ncbi.nlm.nih.gov/bookshelf/br.fcgi?book=dbio&part=A4948 and http://leavingbio.net/TheStructureandFunctionsofFlowers%5B1%5D_files/image005.gif and http://image.tutorvista.com/content/flowering-plants-reproduction/pollen-grain-growth-stages.jpeg B. Male Gametophyte Development
B. Male Gametophyte Development 1. While the female gametophyte is developing, a similar process occurs in the ______________________. 2. Patches of tissue produce ___________________________________. 3. The microsporocytes undergo meiosis to produce tetrads of ______________________. a. The microspores are held together in ____________________________________________. 4. After meiosis, the nucleus in each microspore divides once. a. Each tetrad of microspores separates. b. A two-layered wall develops around each microspore. c. At this point, each microspore is called a ____________________________________________ and is an _______________________________________________________. 5. The outer layer of the pollen grain wall is called the ______________________ and contains chemicals necessary for fertilization. 6. The pollen grain wall may have three thin areas called ______________________ that may help in the maturation of the gametophyte. 7. One of the two nuclei in the pollen grain (____________________________________________) later divides to form ____________________________________________. 8. The other nucleus (________________________________________) is involved in transporting the sperms. V. Pollination A. How is pollination different than fertilization? 1. Pollination is the _________________________________________ __________________________________________________________. 2. Fertilization is the _________________________________________ ___________________________________________________________. B. How does pollination occur? 1. Usually occurs through insects or wind 2. May also be caused by water, birds, bats, other animals, or gravity. C. The characteristics of the flowers reflect their methods of pollination. 1. Wind pollination- flowers are usually ______________________ ________________________________________________________. a. Copious amounts of pollen are formed. b. Often a culprit of seasonal allergies. 2. Bee Pollination- flowers are usually ___________________________ ___________________________________________________________. a. Flowers are usually sweetly fragrant and produce sweet ______________________. b. Bees are dusted with pollen as they take the nectar and then transfer the pollen to the next plants they visit. 3. Beetle Pollination- flowers are usually ______________________ ________________________________________________________. a. Usually produce ______________________, ______________________, or ______________________ odors and may or may not produce nectar. b. ______________________ is often a source of food. 4. Fly Pollination- flowers are often ______________________ or ______________________ in color and have ______________________ odors. a. May have nectars that resemble rotting meat. 5. Moth Pollination- usually occurs at night so flowers tend to be ______________________ or ______________________. 6. Butterfly Pollination- flowers are usually ______________________ with ______________________ 7. Hummingbird Pollination- flowers are usually ______________________ or ______________________ with little ______________________. a. Very few birds have a sense of smell. b. Flowers are similar in structure to butterfly-pollinated flowers but with copious amounts of ______________________ produced. 8. Bat Pollination- flowers usually only open at night. a. Flowers are large or cluster in large inflorescences. 9. Some flowers have become very specialized to be pollinated by a single individual or group of animals. a. If their pollinators become extinct, so do they. VI. Fertilization- after pollination, fertilization may take place. Fertilization may not occur if the pollen is from different species or from the same plant. A. The pollen grain absorbs fluids from the ______________________. 1. The cytoplasm bulges out as a ____________________________________________ breaks through one of the ______________________. B. The pollen tube grows down between the cells of the stigma and ______________________ until it reaches the ______________________. 1. This takes anywhere from about 24-48 hours (over a year in a few plants). C. The ____________________________________________ remains at the tip of the tube. 1. The ____________________________________________ lags behind and divides into ______________________ as it travels. 2. At this point, the germinated pollen grain is the __________________ ___________________________________________________________. D. When the pollen tube enters the micropyle, it discharges its contents into a degenerating ______________________. 1. One sperm fertilizes the ______________________. 2. One sperm fertilizes the ____________________________________ 3. Thus, we have ____________________________________________. E. The fertilized egg becomes the ______________________. F. The fertilized polar nuclei become the _______________________________ ________________________________________________________________. 1. The endosperm nucleus divides by mitosis to become the ____________________________________________, which surrounds the ______________________ that develops from the zygote. 2. In monocots, the endosperm makes up the majority of the seed. 3. In dicots, the endosperm is used up by the embryo by the time the seed is mature. 4. In some plants, the endosperm may be 5n, 9n, or 15n. G. The integuments become the hard seed coat. VII. Alternative Reproduction A. ______________________ - embryo development without development and fusion of ______________________. 1. Two types of apomixes a. In one form, the egg is formed with 2n chromosomes and develops without ever being fertilized. b. In another version, the cells of the ovule (2n) develop into an embryo instead of — or in addition to — the fertilized egg. 2. In the case of apomixis, embryos develop without the contribution of a ____________________________________________. a. The result is that apomictically produced seeds inherit their genes exclusively from the ______________________, and so the plants that grow from these seeds are identical to the mother plant (they are ______________________ of their mother). b. There is very little genetic diversity in these plants & they are prone to ______________________. 3. Hybridization between different species often yields ______________________ offspring. a. In plants, this does not necessarily doom the offspring. Many such hybrids use apomixis to propagate themselves. 5. The many races of __________________________________________ growing in lawns across North America and the many races of ____________________________________________ are two examples of sterile hybrids that propagate successfully by apomixis. 6. Many valuable crop plants (e.g., corn) cannot be propagated by asexual methods like grafting. a. Agricultural scientists would dearly love to convert these plants to apomixis: b. This would make embryos that are genetic clones of themselves rather than the product of sexual reproduction with its inevitable gene reshuffling. c. After 20 years of work, an apomictic corn (maize) has been produced, but it does not yet produce enough viable kernels to be useful commercially. B. ____________________________________________- literally means “___________________________ fruit” 1. development of fruit from ovaries containing unfertilized eggs. Parthenocarpic fruits are devoid of embryo and endosperm (& are therefore devoid of ______________________). 2. Parthenocarpy occasionally occurs as a mutation in nature, but it is a defect, as the plant can no longer reproduce. 3. Several edible fruits have been bred to afford the taste of the fruit without the seed. a. Found in seedless fruits like … C. Other seedless fruits 1. Ovules don’t develop after fertilization 2. Induced parthenocarpy by hormones 3. Hybrids of plants with different chromosome numbers VIII. Collecting Plants A. _____________________________ - library of pressed, dried, preserved plants. 1. Requires a plant press. 2. Plants are initially dried while pressed in newspaper. 3. A final pressing is performed using 100% cotton paper. B. Be very careful when collecting plants. 1. Hundreds of North American plants are listed as sensitive, threatened, or endangered. 2. Permits are usually required for collecting plants in national forests and parks. 3. Photographs are usually preferable and are almost as useful as herbarium collections. |
Some angiosperms have flowers that lack petals. such species are most likely pollinated by
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