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:

The Crassulaceae is composed largely of succulent plants and is similar to the two other large families of succulents, Aizoaceae and Cactaceae, in that it is usually found in hot, exposed, dry, rocky habitats. However, it has a wider range of adaptability, from frost-tolerant alpine to aquatic species.
EXAMINE the flowers on display. Compare the actual floral structure with figures in W&K (p. 215) or lecture notes.  The Crassulaceae is considered to be a relatively primitive member of the Rosidae. What floral characters support this point of view? ____________________________
 

SKETCH the demo plant and flowers.

2. Rosaceae - Rosales:

The Rosaceae is a large, important family of woody and herbaceous plants. It is valued both for its genera of temperate-zone bush and tree fruits (apples, cherries, plums, peaches, almonds, raspberries, pears and strawberries) and for many popular ornamentals. The Rosaceae is quite diverse morphologically, and taxonomic problems arise at all hierarchic levels. In fact, the subfamilies and many tribes have at one time or another been split off from the Rosaceae as separate families.

All members tend to have the similar characters of the androperianth (calyx, corolla, and stamens)-- 5-merous perianth and stamens usually 10-many. It is the differing characters of the gynoecium which separate the subfamilies we study in today's lesson.

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.
SKETCH each sample, CONSTRUCT floral formulas, and identify the respective subfamilies using the information given below:

Subfamily Prunoideae--Gynoecium of a single, simple pistil. Fruit a drupe. Ex: peaches, plums. cherries, apricots, almonds--all from the genus Prunus.

Subfamily Rosoideae--Flower perigynous, gynoecium superior, of many separate pistils (apocarpous), though the hypanthium may be pinched in at the top to make the gynoecium look somewhat inferior. The fruit type varies--it may be a hip (swollen hypanthium with multiple achenes within) as in Rosa, an aggregate of drupelets as in Rubus (dewberry), or a collection of achenes on the surface of a swollen receptacle as in Fragaria (strawberry).
Subfamily Maloideae--Flower epigynous, gynoecium 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.

NOTE The Rosaceae is so diverse that it is nearly impossible to find a single set of recognition characters that can be used to consistently delineate the entire family. The most useful set of recognition characters is: Stipulate herbs, shrubs, and trees with actinomorphic 5-merous flowers, a hypanthium, and many stamens.
 

3. Mimosaceae/Caesalpiniaceae/Fabaceae--Fabales

These three families have been traditionally treated as subfamilies within one large family-- Fabaceae (Leguminosae)--- and are commonly referred to as "legumes." If the family is split, one part retains the name "Fabaceae." In contrast to the Rosaceae, the families of the Fabales 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 floral formulas, and make a family determination for each, using the information given below.

Fabaceae--Flowers zygomorphic, papilionaceous--with banner, wing, and keel petals. Banner positioned 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 among the legumes--soybeans, beans, peas, field peas, chick peas, lentils, etc.--as well as many ornamentals.

Caesalpiniaceae--Flowers zygomorphic and +/- papilionaceous. Banner positioned within wings; keel petals unfused. Stamens usually ten, all free, often of several sizes or shapes. Ex: Cercis (redbud), Chamaecrista (partridge pea).

Mimosaceae--Flowers actinomorphic, borne in dense capitate clusters or racemes. Perianth with varing stages of fusion. Showy part of flower is the usually numerous stamens, often with colorful filaments. Leaves usually bipinnate. Ex: Neptunia (sensitive briar), Prosopis (mesquite)

LEARN to differentiate the families on sight. Also become familiar with the specialized corolla terminology: PAPILIONACEOUS, STANDARD/BANNER, WING, AND KEEL.

4. Oenothera sp.: - Onagraceae - Myrtales:

SKETCH your Oenothera flower. NOTE hypanthium and ovary position. 
 
 

5. Euphorbia and Croton: Euphorbiaceae - Euphorbiales:

The Euphorbiaceae is a large (ca. 7500 species) morphologically variable family. A general set of recognition characters would include: herbs and shrubs often with milky latex; unisexual, often highly reduced flowers with 3-carpellate gynoecium; and mottled carunculate seeds.

NOTE that the family contains two flower types: The "Euphorbia-type" arranged in a CYATHIUM, and the "non-Euphorbia-type", arranged variously. See p. 245 in W&K and wall chart for floral diagrams.

OBSERVE Euphorbia cyathia. Examine the RECEPTACULAR CUP, GLANDS, and GLAND APPENDAGES. 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.
OBTAIN male and female flowers from Croton sp. COMPARE Croton with Euphorbia:



	Euphorbia	Croton
Male flowers (where)	_______________	_______________
Female flowers (where)	_______________	_______________
Number of carpels	_______________	_______________
Calyx present?	_______________	_______________
Corolla present?	_______________	_______________
Inflorescence type	_______________	_______________

SKETCH flowers and inflorescences of both genera.
EXAMINE the characteristic Euphorbiaceae fruit: the three locules with solitary, carunculate seeds. What is the placentation type?_______________.

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

This is the carrot family.  These plants are herbaceous.  The leaves are often divided or compound.  The flowers are usually small, perfect, and regular.  Examine the material available.  Note the characters typical of the family: SIMPLE OR COMPOUND UMBELLATE INFLORESCENCES, SCHIZOCARP FRUIT, and MERICARPS. 
SKETCH the inflorescence and fruit of the Apiaceae.