Laboratory 5: Magnoliopsida, Subclass III
|Objectives for this lab are to:
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. Don't pet the cacti.
- know the characteristics of the subclass Caryophyllidae
- learn key features of families and genera of the
- be able to identify structures in preserved, fresh, or
mounted specimens of Caryophyllidae
- identify to subclass, family, and genus for selected
members of this subclass
study exercises are designed to
you with the major characters of some important flowering plant
Follow the guidelines on your instruction sheets. Answer questions and
diagram structures ON THE SHEETS
and save them to study from.
in addition to those requested in the lab instructions, will be useful.
For exams, you will be expected to be able to identify structures
in preserved or fresh floral material. Herbarium specimens will be on
during each laboratory period. You should be able to identify these to
genus, family, and subclass by recognizing the characters we discuss.
a copy of the overhead presented in lab, click here
In contrast to the anemophilous Hamamelidae, taxa of
Caryophyllidae are typically insect-pollinated (ENTOMOPHILOUS.) Flowers
are often perfect and relatively large and showy.
Work in pairs. OBTAIN a flower. NOTE polypetalous
perianth with gradation from sepaloid to petaloid appendages. This
is the only completely epigynous family of the Caryophyllidae.
spines grow from modified axillary buds (AREOLES)
found only in the Cactaceae. NOTE areoles in axils of the small
leaves on the base of the flower. In Opuntia the areoles bear
barbed hairs called GLOCHIDS. Glochids are restricted to Opuntia.
Following your TA's instructions, CUT a thin cross-section
from your flower, then long-section the remaining upper portion cutting
from the base toward the apex. NOTE the thin, light-colored
wall, and the thick HYPANTHIUM with two layers of tissue. The outer
layer represents stem tissue, i.e., epigyny apparently has been brought
about by recession of the gynoecium into the stem. Presence of
axillary buds (areoles) on the outer surface supports this hypothesis.
long-section; pointing out: hypanthium, ovary, style, stigma,
and perianth. DIAGRAM a cross-section of the ovary. CUT
side of the cross-section slice and "unroll" it to count lines of
Do lines of placentation correspond to the number of stigma lobes?
CONSTRUCT a FLORAL FORMULA for your
flower (compare with W&K, p. 358):
REVIEW family characters as you dissect your flowers. CONSTRUCT
a floral formula and key to genus. Note the modified sheathing
Ocrea are characteristic of many species in the Polygonaceae.
These three examples from the Caryophyllidae
a demonstration of the perianth diversity encountered in this subclass.
Examine additional representative members of the Caryophyllidae
FLORAL FORMULA: ______________________________
KEY TO GENUS: ________________________________________________________________
FRUIT TYPE: _____________________
SKETCH YOUR POLYGONUM :
(many weeds), beets, Swiss
Amaranthaceae--reduced flowers--Amaranthus (pseudocereals, weeds), Celosia
(a popular bedding plant)
Portulacaceae--2 sepals, flowers open only
on sunny days--Portulaca
(weeds, bedding plants), Claytonia
Phytolaccaceae--primitive in subclass--Phytolacca
Nyctaginaceae--corolla absent; calyx
(local endangered species), Mirabilis
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last updated Juen 25, 2010