Laboratory 7: Magnoliopsida, Subclass 5


Objectives for this lab are to:
  • know the characteristics of the subclass Rosidae
  • learn key features of families and genera of the Rosidae
  • be able to distinguish subfamilies of the Rosidae by gynoecium and fruit characters
  • be able to distinguish families of the Fabales by androperianth characters
  • be able to identify structures in preserved, fresh, or mounted Rosidae
  • identify subclass, family, and genus for selected members of this subclass.
Safety concerns for this lab:  Use caution with dissecting tools, wear protective eyewear if working with specimens preserved in Carosafe, dispose of Carosafe specimens in proper waste container.  Use preserved  Euphorbia if you are sensitive to the sap of fresh plants. 

Note: Family study exercises are designed to acquaint you with the major characters of some important flowering plant families. Follow the guidelines on your instruction sheets. Answer questions and diagram structures ON THE SHEETS and save them to study from. Diagrams, in addition to those requested in the lab instructions, will be useful. For exams, you will be expected to be able to identify structures present in preserved or fresh floral material. Herbarium specimens will be on display during each laboratory period. You should be able to identify these to genus, family, and subclass by recognizing the characters we discuss. For a copy of the overhead presented in lab, click here.

The Rosidae is a very large subclass. It has the most families of any subclass. Unifying characters include showy flowers, perianth parts usually free, and stamens as many as or more than the petals.

1. Crassulaceae - Rosales - Demonstration:


2. Rosaceae - Rosales:

3. Mimosaceae/Caesalpiniaceae/Fabaceae--Fabales


4. Oenothera sp.: - Onagraceae - Myrtales:

EXAMINE the herbarium specimens and OBTAIN a flower for dissection and observation.
CONSTRUCT a floral formula and then key to family. The fruit will be a capsule.
FLORAL FORMULA ________________________
KEY TO FAMILY___________________________________________________

Both the Onagraceae and Brassicaceae are characterized by a 4-merous calyx and corolla, and might be confused at a quick glance. LIST three characters that will always differentiate these two families.
Onagraceae  vs. Brassicaceae
1.____________________ 1.____________________
2.____________________ 2.____________________
3.____________________ 3.____________________

SKETCH your Oenothera flower. NOTE hypanthium and ovary position

5. Euphorbia and Croton: Euphorbiaceae - Euphorbiales:


6. Chaerophyllum and/or Polytaenia: - Apiaceae - Apiales

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last updated June 25, 2010 by MDR