Week 11 Laboratory

Lower Asterids & Core Asterids (part I)


<Lab Schedule> <Next Lab>


I. Detailed floral dissections. This week we will be looking at the "lower" asterids and the first half of the "core" asterids or euasterids. Provided will be two examples of families in the "core" asterid group. Before you look at these examples and later demonstrations, recall what features of the perianth, stamen number, and carpel number define the Asterids. Include this section in your laboratory notebook with illustrations and labeled parts. Refer to Plant Systematics [T], Zomlefer [Z], and Gleason & Cronquist for descriptions of the species and families as needed.

 

A. Asclepias curassavica   (Asclepiadaceae or now Apocynaceae— milkweed) (pp. 301-304 [T], 239-243 [Z])Exacum affine (Gentianaceae - persian violet) (pp. 305-306 [T], 244-246 [Z])

Refer to the lecture handout provided and be able to recognize and find the structures called corona, hood, gynoestegium, and pollinia.  Refer to the wall chart that depicts all these features in nice detail. Attempt to mimic a pollinator by removing the pollinia and inserting them back into the stigmatic crevice.

Give a floral formula for Asclepias

 

B. Pentas lanceolata (Rubiaceae - star cluster) (pp. 305, 307 [T], 236-239 [Z])

Pentas is a tropical woody genus. You should be able to recognize this genus as belonging to the family Rubiaceae based on a distinctive feature found between the always opposite leaves; what is this structure called?

Note the position of the perianth relative to the gynoecium; what kind of flower is this? The family shows variable numbers of ovules/seeds in its gynoecium. How many carpels and how many ovules per carpel do you see?

Give a floral formula for Rubiaceae (how will temperate genera differ from Pentas?).

 


II. Demonstration floral dissections. Look at these in as much detail as you want, but be sure to identify and understand the characters indicated on the sheet next to each floral dissection.

A. Rhododendron (Ledum) sp. (Ericaceae - Labrador tea, "Lower Asterid") (pp. 293-295 [T], 77-81 [Z])


B. Exacum affine (Gentianceae - persian violet((pp. 305-306 [T], 244-246 [Z])
)

C. Salvia coccinea (Lamiaceae or Labiatae - salvia, sage) (pp. 308-313 [T], 265-270 [Z])


III. Additional representatives of these and other families are placed around the room. As time permits, examine these plants and especially note the floral structures. You will not be required to know these plants; they are simply provided to illustrate additional members of these families. LA = "lower" asterid

A. Rhododendron micranthum & other species (Ericaceae - rhododendron, azalea) LA
B. Erica (Ericaceae - heather) LA
C. Ledum (Ericaceae - heather) LA
D. Cornus mas (Cornaceae - dogwood) LA
E. Impatiens (
Balsaminaceae - jewel weed, touch-me-not) LA
F. Sarracenia sp. (Sarraceniaceae - pitcher plant) LA
G. Exacum affine (Gentianaceae - persian violet)
H. Nerium oleander (Apocynaceae - oleander)
I. Galium odoratum (Rubiaceae - bedstraw)
J. Coffea arabica (Rubiaceae - coffee)
K. Solanum pseudocapsicum (Solanaceae - Jerusalem cherry)
L. Nicotiana (Solanaceae - tobacco)
M. Capsicum sp. (Solanaceae - pepper)
N. Brugmansia (Datura) sp. (Solanaceae - Angel's trumpet)
O. Petunia x hybrida (Solanaceae - garden petunia)
P. Ipomoea batatus (Convolvulaceae - sweet potato)
Q. Heliotropium arborescens (Boraginaceae - heliotrope)
R. Lantana camara (Verbenaceae - yellow sage)
S. Clerodendrum (Verbenaceae or now Lamiaceae - glory bower)
T. Antirrhinum majus (Scrophulariaceae or now Plantaginaceae - snapdragon)
U. Justicia brandegeana (Acanthaceae - shrimp plant)
V. Streptocarpus sp. (Gesneriaceae)
W. Aeschynanthus sp. (Gesneriaceae)

 

IV. 15 genera of Wisconsin plants to be able to identify on site. LA = "lower" asterid

1. Chamaedaphne (Ericaceae - leatherleaf) LA
2. Primula [formerly Dodecatheon] (Primulaceae - shooting star) LA
3. Phlox (Polemoniaceae - phlox) LA
4. Cornus (Cornaceae - dogwood) LA
5. Gentiana (Gentianaceae - gentian)
6.
Asclepias (Asclepiadaceae or now Apocynaceae - milkweed)
7. Galium (Rubiaceae - bedstraw)
8. Solanum (Solanaceae - bittersweet, nightshade)
9. Convolvulus (Convolvulaceae - bindweed)
10. Lithospermum (Boraginaceae - puccoon)
11. Monarda (Lamiaceae - horsemint, wild bergamot)
12. Verbena (Verbenaceae - vervain)
13. Pedicularis (Scrophulariaceae or now Orobanchaceae - lousewort, wood betony)
14. Penstemon (Scrophulariaceae or now Plantaginaceae - turtlehead)
15. Plantago (Plantaginaceae - plantain)

 

V. Keying: you should be making progress on your plant collections by identifying your specimens to species. Find some unidentified specimens in your collection that belong to the Lower Asterids or Euasterids (families covered in this lab) and key them to species.

up