1. Gossypium or Callirhoe (winecup) Malvaceae - Malvales:

OBTAIN a flower and note the involucral bracts. The bracts in this family often have a calyx-like appearance and are termed the EPICALYX. The true calyx is synsepalous; the corolla is PENTAMEROUS (5-parted) and actinomorphic. Remove calyx and corolla. COMPARE what you see against fig. 16-13 (p. 330) in W&K and with the wall chart. The stamens are _________________ i.e., the androecium forms a single unit that can be easily removed from the gynoecium. Remove the androecium, observe the HYPOGYNOUS nature of the flower, and cross-section the ovary. 

DIAGRAM  your section, pointing out placentation and carpel number:

FLORAL FORMULA ________________________________
KEY TO FAMILY (leaves not gland-dotted): __________________________________________

2. Salix sp. (willow) - Salicaceae - Salicales:

OBTAIN staminate and pistillate inflorescences and examine under high magnification. NOTE that the staminate flower is apetalous, is subtended by a single bract, and has small glands between the bract and filament (seeW&K fig. 16-16, p. 336 and the poster on the wall).
FLORAL FORMULA: ______________________
SKETCH (staminate)
The pistillate flowers of Salix are also without a perianth. NOTE gland in the axil of the pedicel. Glands in Salix produce nectar, i.e., insects play a pollination role in species of this genus.
REMOVE a single pistillate flower. NOTE BICARPELLATE, SYNCARPOUS gynoecium with two styles. Under high magnification, tease open the ovary and note_________________ placentation and COMOSE ovules. The COMA (tuft of hairs) will serve as a wind dispersal mechanism for the mature seeds. This multi-ovulate ovary, which matures to form a capsule, distinguishes the amentiferous Salicales from morphologically similar taxa of the subclass Hamamelidae.
FLORAL FORMULA: ______________________
SKETCH (pistillate)
KEY TO FAMILY: __________________________________________________________

3. Brassica sp. (mustard) - Brassicaceae (Cruciferae) - Capparales:

OBTAIN a single flower. Examine and construct a floral formula (tease open the ovary under high magnification and note lines of placentation to determine carpel number).
FLORAL FORMULA: _________________________________
DIAGRAM the gynoecium and androecium of this flower:
COMPARE your floral formula and diagram with p. 338 in W&K and with the poster. What is the term for this type of stamen arrangement? ___________________
KEY TO FAMILY (leaves neither punctate nor bristly-glandular): _________________________________________________________________
EXAMINE the key to genus for this family and note that identification requires a specimen with FRUIT. This is the case with many other angiosperm families, and is one reason why a complete specimen is essential. 

4. Gaylussacia or Vaccinium sp. - Ericaceae - Ericales:

OBTAIN a flower and examine it.

CONSTRUCT a FLORAL FORMULA: ________________________________  Refer to fig. 16-18 b, c, d, l, n  (p. 340) in W&K.


SKETCH the corolla and androecium.

DETERMINE

a. anther dehiscence: ___________________
b. placentation : _______________________
c. ovary position: ______________________
d. corolla shape : ______________________

5. Cucumis sativus (cucumber) - Cucurbitaceae - Violales:

OBTAIN a staminate and a pistillate flower. Develop a floral formula for each. 


MALE FLORAL FORMULA ____________________
FEMALE FLORAL FORMULA _____________________
 

CROSS-SECTION the ovary and count cells.   DETERMINE the nature of connation in the androecium.
LOCATE the nectary disk in each sex.
DRAW the male and female flowers of Cucumis:


What vegetative characters are associated with the Cucurbitaceae? ____________________________________
 
 

Carnivorous Plants

Some of the most interesting members of the Dilleniidae are carnivorous plants. These plants usually live in acid bogs which have soils low in nutrients (especially Nitrogen). To supplement their "diet", these plants trap and digest insects.
 
Sarraceniaceae--Sarracenia--Pitcher plant. Leaves tube-shaped. Insects fall into the pool of liquid at the base of the pitcher and are unable to climb out. Flowers hang upside down and have a large, umbrella-like stigma.

Droseraceae--Drosera--Sundew. Leaves in a rosette. The leaves are covered with glandular hairs which produce a sticky mucilage. Insects attracted to the sweet smell are caught fast and digested. The flowers are usually pink.

Droseraceae--Dionaea muscipula--Venus Fly-trap. The leaves grow in a rosette. Each is a snap-trap. An insect walking on the trap triggers tiny hairs, causing the trap to snap shut. Inside, the insect is slowly digested, and when digestion is complete the trap opens again. Each trap can only close and open a few times, so new traps are always being produced.
 


NOTE--Carnivorous plants should usually not be collected from the wild. Many are becoming rare in their natural habitats and most will not withstand transplantation. If you want to experiment with growing them, buy them from a reputable nursery.
 
 




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last updated 16 February 2005 by MDR