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Chapter 23a-Angiosperms The most diverse group of plants, with about 14,000 genera and 257,000 species. How do angiosperms differ from gymnosperms? 1)The ovules of angiosperms are borne inside carpels, instead of on scales as in gymnosperms. 2) Angiosperms have flowers instead of the cones of gymnosperms. 3) A unique part of the life cycle of angiosperms is doublefertilization. In double-fertilization, the two sperm nuclei in the pollen tube each participate in a fertilization event. 4) Another key feature in angiosperms is the rapid reproductive cycle. Many gymnosperms are slow growing and have lengthy reproductive cycles. Angiosperms can have very rapid reproduction, Major Angiosperm Clades The relationships of major angiosperm groups are modeled after the Angiosperm Phylogeny Group 2009 system (APGIII 2009). APG III 2009 -classifies one to several families into orders where there is strong evidence that the order is monophyletic -these designated orders do not represent a hierarchical classification system Orders can be viewed as convenient placeholders for 1 or more families that appear to comprise a monophyletic group. Some monophyletic groups that contain several orders are given names. Ex: Magnoliids Basal Angiosperms Major Angiosperm Clades Basal angiosperm groups: Many phylogenetic analyses agree in placing Amborella trichopoda (Amborellaceae) as sister to all of the flowering plants. This means that Amborella trichopoda is a descendent Amborella trichopoda is a small, evergreen, shrub of New Caledonia. It only occurs in the moist, shaded understory of tropical mountainside forests. Nymphaeaceae Nymphaeaceae (water lilies) and Cabombaceae (water shields) are successive sister groups to all other angiosperms. The water lilies represent the form of basal angiosperms. Radially symmetrical flowers with tepals (undifferentiated petals and sepals). Nymphaeaceae-Arkansas flora Nuphar advena [syn. N. lutea] Nymphaea odorata subsp. odorata [syn. N. odorata] Monocot Eudicot The old group dicot included all the angiosperms other than Monocots. Recent molecular studies do not support the simple division of angiosperms into dicots and monocots. Basal Angiosperms Dicot is no longer used to designate an angiosperm lineage because it is not monophyletic http://watchingtheworldwakeup.blogspot.com The core angiosperms comprise three lineages: The Magnoliids Mostly tropical, subtropical, and warm temperate. The seeds are borne on an almost cone-like structure For many years, the simple Magnolia flower was thought to represent the primitive angiosperm flower The Magnoliids include many commercially important plants including: Myristica fragrans Persea americana Piper nigrum Magnoliids common in Arkansas include: Magnolia grandiflora Asimina triloba Sassafras albidum The Monocots Monocots are distinguished from other angiosperms by the presence of a single cotyledon (seed leaf). Major monocot groups are the Note the flower parts in threes and the leaves with parallel venation, all typical of monocots. Monocots in the human diet http://botanistinthekitchen.wordpress.com The Eudicots The eudicots are separated from all other angiosperms by a special pollen form. Tricolpate pollen Basal Angiosperms The eudicots include three major lineages. http://botanistinthekitchen.wordpress.com Core eudicot food plants, with rosids (green branch) and asterids (red branch) collapsed. The Eudicots http://botanistinthekitchen.wordpress.com Rosid major clades with food species http://botanistinthekitchen.wordpress.com Rosid major clades with food species Food in the fabids http://botanistinthekitchen.wordpress.com http://botanistinthekitchen.wordpress.com Food in the malvids Flowers The parts of the flower are arranged in successive whorls above the receptacle. The first whorl is composed of sepals. The sepals are collectively referred to as the calyx. The second whorl is made up of petals. The petals are collectively referred to as the corolla. The petals and sepals together are called the perianth. The next whorl of the flower is the androecium, comprised of stamens. The stamens have 2 parts, the slender filament and the anther, which rests on top of the filament. The androecium is the male portion of the flower, where the pollen is produced. The final whorl is the gynoecium, the female part of the flower. The gynoecium comprises one or more carpels. The pistil can either be a single carpel or multiple carpels fused together. At the base of the pistil is the ovary, where the egg cells are formed and fertilization occurs. An elongate style elevates the stigma above the ovary. The stigma is where pollen lands, which is the first step toward fertilization of the egg. The Androecium: structures of the anther. Each pollen sac produces a number of microsporocytes. Each microsprocyte undergoes meiosis to produce four haploid microspores. The nucleus of each microspore then divides without cytokinesis to form the pollen grain with 2 nuclei. The pollen grain wall has a pattern that varies widely among different types of angiosperms. When the pollen grains are mature, the anther walls break open and the pollen is released. Through the process of pollination, the pollen is transported to the stigma of the same or a different flower. The pollen grain germinates, The Gynoecium: structures of the carpel. simple pistil More often, there are several separate carpels or fused carpels. Inside the locules, the ovules are attached to the ovary by special tissue called placenta (plural placentae). The ovary has one to several chambers called locules. Study outline for Chapter 23a-Angiosperms Name four ways that angiosperms differ from gymnosperms. Define double-fertilization. The relationships of major angiosperm groups are modeled after the _________________________. Name the basal angiosperm groups. Describe specific characteristics for Amborella. Describe specific characteristics for the water lily group. What are the core angiosperm lineages? Describe specific characteristics for the Magnoliids Name three commercially important plants that are included in the Magnoliids. Name three plants that are common in Arkansas and included in the Magnoliids. What are the main differences between eudicots and monocots? Describe general characteristics for monocots. Name food examples for monocots. Name the 3 main eudicot lineages. Name food examples for the core eudicots. Name food examples for the asterids. Name food examples for the rosids. Study outline for Chapter 23a-Angiosperms Define the following terms and label the image provided: receptacle perianth androecium gynoecium sepal calyx petal corolla stamen anther filament carpel pistil stigma style ovary Define the following terms for the structure of the androecium, label the image provided and answer the questions: anther pollen sacs microsporocytes microspores pollen grain generative cell nucleus tube cell nucleus germinated pollen grain pollen tube What cell division process happens here? What cell division process happens here? How many microspores? What is the male gametophyte? Haploid or diploid? What is the difference between a simple and a compound pistil? Define locule. Define placenta.
