Caryophyllidae

Objectives for this lab are to:

know the characteristics of the subclass Caryophyllidae
learn key features of families and genera of the Caryophyllidae
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

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.

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.

1. Opuntia-Cactaceae-Caryophyllales:

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. Cactus 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 small barbed hairs called GLOCHIDS. Glochids are restricted to Opuntia.

Following your TA's instructions, CUT a thin cross-section slice from your flower, then long-section the remaining upper portion cutting from the base toward the apex. NOTE the thin, light-colored ovary wall, and the thick HYPANTHIUM with two layers of tissue. The outer "hypanthium" layer represents stem tissue, i.e., epigyny apparently has been brought about by recession of the gynoecium into the stem. Presence of leaves and axillary buds (areoles) on the outer surface supports this hypothesis.

DIAGRAM your long-section; pointing out: hypanthium, ovary, style, stigma, androecium and perianth. DIAGRAM a cross-section of the ovary. CUT one side of the cross-section slice and "unroll" it to count lines of placentation. Do lines of placentation correspond to the number of stigma lobes? _______________
CONSTRUCT a FLORAL FORMULA for your flower (compare with W&K, p. 358): ____________________________________
FRUIT TYPE:____________

2. Arenaria-Caryophyllaceae-Caryophyllales:

OBTAIN a flower and an immature fruit. The flowers are easier to dissect in shallow water. Carefully "open" the flower, noting calyx, corolla, androecium, and gynoecium. Take care in splitting open the pericarp of the developing fruit. (If fruit are scarce, see a demo.)
What type of placentation is this?_______________________
What type of fruit is characteristic for this family?___________________________
CONSTRUCT a floral formula for this plant: ___________________________

SKETCH your Arenaria flower and fruit:

3. Polygonum-Polygonaceae-Polygonales:

REVIEW family characters as you dissect your flowers. CONSTRUCT a floral formula and key to genus. Note the modified sheathing stipules, the OCREA. Ocrea are characteristic of many species in the Polygonaceae.
FLORAL FORMULA: ______________________________
KEY TO GENUS: ________________________________________________________________
FRUIT TYPE: _____________________
SKETCH YOUR POLYGONUM :

These three examples from the Caryophyllidae

Chenopodiaceae--reduced flowers--Chenopodium (many weeds), beets, Swiss chard

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 (spring beauty)

Phytolaccaceae--primitive in subclass--Phytolacca (pokeweed)

Nyctaginaceae--corolla absent; calyx petalloid--Abronia (local endangered species), Mirabilis (four-o'clock)

last updated Juen 25, 2010 by MDR

Laboratory 5: Magnoliopsida, Subclass III

Caryophyllidae

1. Opuntia-Cactaceae-Caryophyllales:

2. Arenaria-Caryophyllaceae-Caryophyllales:

3. Polygonum-Polygonaceae-Polygonales: