BIOLOGY 366 PLANT SYSTEMATICS FINAL EXAM 100 POINTS SECTION 1 (Short answer; 35 points total): Read the questions carefully. Be as precise as possible in your answers. 1. What is a pseudanthium? Give two examples of pseudanthia, each one from a different family, and compare and contrast them. 5 points 2. The Poaceae, Juncaceae and Cyperaceae are important in many habitats, especially wetlands, and they often grow side by side. Can you tell them apart? Fill in the following table of distinguishing characteristics for these three families. 4 points Character Juncaceae Cyperaceae Poaceae Stem shape Terete Leaf sheaths Closed Open Inflorescence structure Perianth Cymose Spikelet Lodicules Fruit Achene Page 1
3. You have seen examples of independent, repeated evolution (homoplasy) of many different traits. Ten of these are listed below; fill in families that exhibit these traits (or that include genera or groups of genera that exhibit these traits). 6 points total Trait(s) showing convergence Family # 1 Family #2 Epiphytism Animal-dispersed fruits Pollinia Latex Pellucid dots in the leaves Stem succulence 4. Stems and leaves sometimes are shaped by evolution to acquire novel appearances and/or functions. (A) Taking a typical herbaceous stem and a typical flat green dicot or monocot leaf as your starting points, define two specialized stem types and two specialized leaf types. (B) Describe how you might determine whether a particular part is homologous to a leaf or a stem. 6 points Page 2
5. The development of molecular data techniques revolutionized plant systematics. Discuss why molecular data are considered to be superior to traditional morphological data in terms of character number, number of character states, and convergent evolution. 4 points 6. Match each taxon on the left with the most appropriate adaptation from the column on the right. Put your answer in the 2 nd column. Each taxon and adaptation must be used only once. (1 point each, 10 points total) Taxon Answer Adaptation Apiaceae A Primarily on acidic soils Orobanchaceae Ericaceae Lobelia Lamiaceae Asclepias Oleaceae B Two stamens C Gynobasic style D Pollen plunger mechanism E Interpetiolar stipules F Stylopodium G Parasitic Convolvulaceae H Resupinate flowers Asteraceae Rubiaceae I Corona J Petals twisted in bud Page 3
SECTION 2 (45 points total): Phylogenetics, Speciation and Nomenclature The two intrepid botanists Kevin Day and Leanne Martin are collaborating to study the systematics and ecology of the core tricolpate family Yuraceae. They have completed extensive field work in the prairie and woodland habitats occupied by the species of this family that occur in the Midwest. They find a total of 10 species and conduct a molecular phylogenetic analysis. The phylogeny they recover is shown on the handout, along with the morphological synapomorphies that support the clades they found. Kevin and Leanne also found a few populations of an unusual entity that does not fit well into the established phylogeny or classification. Examine the phylogeny, the summary list of taxa below (with the date of publication of the species in parentheses), and the additional information to answer the questions that follow. Weera nitida Wendel (1990) Yura obnoxia Wendel (1990) Yura foetida Wendel (1990) Ima moronica Limbaugh (1980) Yura beatifica Wallace (1995) Ima peppa L. G. Clark (1986) Yura messa R. W. Pohl (1960) Ima nerda L. G. Clark (1986) Yura confusa R. W. Pohl (1964) Yura peppa Wallace (1995) Ima is characteristic of prairies, Yura is found in woodlands or woodland edges (with Y. obnoxia and Y. foetida being restricted to wet areas along streams), and Weera is a rare species of wet prairie potholes. The unusual entity grows in woodlands, always near populations of Yura foetida. It has a scrambling, not quite vining habit, deeply pinnately lobed leaves that are faintly white-striped, flowers with pink, basally connate petals, and a musky scent. Kevin and Leanne were able to determine that it has a chromosome count of 2n = 42. Kevin and Leanne also decided that because Yura obnoxia and Yura foetida differ in ecology, chromosome number, leaf morphology and pollination syndrome from the other Yura clade, they are going to elevate this clade to the status of a new genus, Itsa. 1. What is the phylogenetic term that describes both genera Ima and Yura as they appear in the molecular phylogeny of Yuraceae? 2 points 2. What will be the new names for Yura obnoxia Wendel and Yura foetida Wendel when they are transferred to the new genus Itsa by Martin and Day? 4 points 3. What needs to happen to the name Ima nerda L. G. Clark, based on the results of the phylogenetic analysis? What will be the new name for this species? 4 points Page 4
4. What will happen to the name Yura peppa Wallace and why? Help Leanne and Kevin by picking out a new name for this species. 4 points 5. Now let s sort out the unusual entity that Kevin and Leanne observed and collected in during their field work. What is the best explanation for its chromosome number? Is its morphology consistent with what you know about the probable derivation of the chromosome number how so? Which two species are the most likely progenitors? 6 points 6. Should this entity be described as a new species why or why not? 4 points 7. Give one example of a character state that is plesiomorphic for Yuraceae in this analysis. Give one example of a synapomorphic character state for a clade within Yuraceae. Give one example of an autapomorphic character state in this cladogram. 6 points total Plesiomorphic: Synapomorphic: Autapomorphic: Page 5
8. Fill in the remaining cells in the comparative table for the four genera of Yuraceae shown in the phylogeny. 7 points Character Weera Ima Itsa Yura Leaf structure (simple vs. compd.) opposite opposite Flower smell rotten sweet Petal color red red Petal fusion free free Nectary type nectar spur disk at ovary base Stamen number 10 5 Fruit type berry berry 9. Write a dichotomous key to the four genera using the characters and character states in the table in question 8. Each lead must contain at least two characters and key leads must be parallel. 8 points Extra Credit: If the unusual entity is described as a new genus, what is one possible name for it according to the ICBN? 2 points Page 6
SECTION 3 (True/False; 2 points each, 20 points total): If a statement is true, mark a T next to it. If the statement is false, mark an F next to it and then indicate how you would correct it to make it true, as in the example below. Note that simply inserting or deleting the word not is not sufficient to correct a false statement. Example: The Earth is flat. 1. A complete flower must be a perfect flower. 2. If an egg cell of an angiosperm contains 10 chromosomes, then the cells of the gametophyte that produced it will each contain 20 chromosomes. 3. When you eat celery, you are eating the main stem of the celery plant. 4. All seed plants are heterosporous. 5. The presence of woody stems in gymnosperms is considered plesiomorphic. 6. A megasporophyll bearing marginal ovules is homologous to an angiosperm carpel. 7. Natural rubber is derived from the latex of a plant in the Euphorbiaceae. 8. The spathe in the Araceae is a modified calyx. 9. Tubular flowers with a red corolla and floral nectaries are expected to have bat pollination. 10. Synapomorphies for Cupressaceae include 2 inverted ovules per cone scale and seeds with a long terminal wing. Extra Credit: Which seed plant family that we discussed this semester was likely to have had its seeds dispersed by dinosaurs? 2 points Page 7