BOT 360F - Families of Vascular Plants

Quiz 11 7-Dec-10

(1) Please identify the flowering plant families represented by the 10 on-screen images, or answer the question shown. [5 marks; actually, 5.5]

     

(a) Asteraceae (Helianthus)

 

(b) Rosaceae (Rosa); achene

 

 
(c) The gynoecium is syncarpous (Allium) Allium (d) Poaceae (Panicum) Poaceae; Panicoid spikelet
(e) Fabaceae (Desmodium) Desmodium (f) Monocot (cf. Lilium, Tulipa) floral diagram
(g) Rosaceae (Pyrus); Spiraeoideae (half mark for Maloideae)   (h) by wind (Thalictrum) Thalictrum
(i) Brassicaceae (Cakile) Cakile (j) x, megagametophyte (forms before fertilization occurs); y, embryo sporophyte  

(2) Based on the examples you’ve seen in this course, which do you think is likely to be responsible for more variation in flower and fruit structure: animals or wind? If you have time, explain with examples. [1 mark, plus extra credit for a plausible explanation]

  • Animals.
  • Wind is a single, abiotic factor that arguably has changed little or not at all during the course of biotic evolution. As a consequence, there is a limited range of changes in reproductive organization that need to be made in order for plants to use moving air to disperse their spores, seeds, or fruits. This in turn means that we see abundant examples of the parallel evolution of small size (e.g. spores, seeds of Ericaceae, Orchidaceae), of parachutes (e.g. modifications of the pappus in Asteraceae; seed hairs of Salicaceae; saccate pollen in Pinaceae), and wings (e.g. winged seeds of Pinaceae; winged fruits in many flowering plant families).
  • Animals evolve and diversify, and coevolve repeatedly with plants. Plants compete with each other to obtain the services of animals for spore and seed dispersal, and with animals in order to avoid predation of those spores and seeds. Inevitably, these ramifying interactions lead to greater diversity than is the case with wind.

 

Images © Royal Ontario Museum 2004.

 


| What are plant families? | How do we distinguish them? | How and why do we study them? | Selected vascular plant families of Ontario | Reading List | Course outline |

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