Laboratory 7: Magnoliopsida, Subclass 5
|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. Use preserved Euphorbia if you are sensitive to
the sap of fresh plants.
- 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
- identify subclass, family, and genus for selected members
of this subclass.
study exercises are designed to acquaint
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
The Rosidae is a very large subclass. It has
most families of any subclass. Unifying characters include
flowers, perianth parts usually free, and stamens as many as or more
1. Crassulaceae - Rosales - Demonstration:
2. Rosaceae - Rosales:
The Rosaceae is a large, important family of woody and herbaceous
It is valued both for its genera of temperate-zone bush and tree fruits
(apples, cherries, plums, peaches, almonds, raspberries, pears and
and for many popular ornamentals. The Rosaceae is quite diverse
and taxonomic problems arise at all hierarchic levels. In fact, the
and many tribes have at one time or another been split off from the
as separate families.
All members tend to have the similar
characters of the androperianth (calyx, corolla, and
5-merous perianth and stamens usually 10-many. It is the differing
of the gynoecium which separate the subfamilies we study in today's
EXAMINE each of the three samples (A,B,C) at the side table.
COMPARE the sample material with the diagrams and subfamily
descriptions with lecture notes, diagrams and descriptions in W&K
(p. 220-223), and wall charts.
sample, CONSTRUCT floral formulas, and identify the respective
using the information given below:
NOTE The Rosaceae is so diverse that it is nearly impossible
find a single set of recognition characters that can be used to
delineate the entire family. The most useful set of recognition
is: Stipulate herbs, shrubs, and trees with actinomorphic 5-merous
a hypanthium, and many stamens.
of a single, simple pistil. Fruit a drupe.
Ex: peaches, plums. cherries, apricots, almonds--all from the genus Prunus.
superior, of many separate pistils (apocarpous), though the hypanthium
may be pinched in at the top to make the gynoecium look
inferior. The fruit type varies--it may be a hip
(swollen hypanthium with multiple achenes within) as in Rosa,
aggregate of drupelets as in Rubus
(dewberry), or a collection of achenes on the surface of a swollen
as in Fragaria
inferior, of about 2 to 5 united carpels. The fruit is a pome,
with a layer of receptacle/hypanthium tissue surrounding the ovary. Ex:
pears, apples, quince, hawthorn.
These three families have been traditionally treated as subfamilies
within one large family-- Fabaceae (Leguminosae)--- and
commonly referred to as "legumes." If the family is split, one part
the name "Fabaceae." In contrast to the Rosaceae, the families of the
share characters of the gynoecium and
legume fruit and differ in characters of the androperianth.
EXAMINE the three samples.
COMPARE the sample material with the descriptions and
diagrams in W&K (p. 224-227) and with
lecture notes and wall charts. SKETCH the samples, CONSTRUCT
and make a family determination for each, using the information given
papilionaceous--with banner, wing, and keel petals. Banner
outside wings; keel petals fused. Stamens usually diadelphous--9
united by filaments in one group and the tenth stamen free. Ex: Lupinus
(bluebonnet). This family contains most of the important food crops
the legumes--soybeans, beans, peas, field peas, chick peas, lentils,
well as many ornamentals.
LEARN to differentiate the families on sight. Also become
with the specialized corolla terminology: PAPILIONACEOUS,
WING, AND KEEL.
zygomorphic and +/- papilionaceous. Banner positioned within wings;
petals unfused. Stamens usually ten, all free, often of several
sizes or shapes. Ex: Cercis
clusters or racemes. Perianth with varing stages of fusion. Showy
of flower is the usually numerous stamens, often with colorful
(sensitive briar), Prosopis
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
LIST three characters that will always differentiate these two
SKETCH your Oenothera flower. NOTE hypanthium
Euphorbiaceae - Euphorbiales:
The Euphorbiaceae is a large (ca. 7500 species) morphologically
family. A general set of recognition characters would include: herbs
and shrubs often with milky latex; unisexual, often highly reduced
with 3-carpellate gynoecium; and mottled carunculate seeds.
Go on with the
NOTE that the family contains two flower types: The
"Euphorbia-type" arranged in a CYATHIUM,
and the "non-Euphorbia-type",
variously. See p. 245 in W&K and wall chart for floral diagrams.
OBSERVE Euphorbia cyathia.
Examine the RECEPTACULAR CUP, GLANDS, and GLAND
Locate the staminate and pistillate flowers. Note the numerous sterile
appendages. Be sure you can identify a cyathium (unique to the genus Euphorbia)
and its component parts.
female flowers from Croton sp. COMPARE Croton
SKETCH flowers and inflorescences of both genera.
|Male flowers (where)
|Female flowers (where)
|Number of carpels
EXAMINE the characteristic Euphorbiaceae
fruit: the three locules with solitary,
carunculate seeds. What is the placentation type?_______________.
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