Lab 10: Violets, Aspens, and Gourds


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Plants to key out (and learn):
71. Hypericum perforatum (Hypericaceae) 'Common St. John's-wort'
The former name for the family of this plant is Clusiaceae. Many of you may have heard of this plant in the context of its medicinal properties. It is an alleged herbal remedy for depression posting retail sales of over $500 million annually in the U.S. The specific epithet, perforatum, may be in reference to the black "perforations" on the undersides of the petals. In WI it is considered an ecologically invasive weed.

72. Viola sororia (Violaceae) 'Common blue violet'
This species is common across the state, found in all but two counties. You will likely encounter this species in lawns, as well as forest sites. The petals can range from, well, violet to blue to white. When keying plants of this genus you must look at the presence/absence of leafy stems, petal color and pubescence, and leaf shape. This is a species that you should know, as it is the official state flower of Wisconsin!

Species to learn:

73. Viola pubescens (Violaceae) 'Yellow forest violet'
This species of violet is also very common across Wisconsin, especially in a variety of forests. Like other violets, the flowers are zygomorphic, however the petals are yellow in this species. You should also notice the presence of leafy stems in Viola pubescens. Contrast this to species number 72. Be ready to see both of these species at your field sites this spring.

74. Populus tremuloides (Salicaceae) 'Quaking aspen'
This member of an important family (Salicaceae) gets its name from its strongly flattened petioles. This causes the leaves to quake or tremble with the slightest wind. Be sure to get a good idea of what catkin inflorescences look like. This is an early colonizing species and its bark is the favorite food of the beaver.

75. Euphorbia esula (Euphorbiaceae) 'Leafy spurge'
This noxious weed, introduced from Eurasia, is something that you will certainly come across in the field. The small flowers are subtended by leaves that are shaped differently from the cauline (attached to the stem) leaves. It has a milky latex. What do you think might be the pollinator for this species?

76. Echinocystis lobata (Cucurbitaceae) 'Spiny cucumber'
This viny weed is often found climbing trees and shrubs that grow along river bottoms, swamps and other wet areas. Its foliage is easily identified by its alternate star-shaped leaves, each with 5 to 7 lobes. Male flowers form clusters, female flowers occur singly. When ripe the 2" long spiny pods burst open and eject four brown or black seeds.

Genera to learn:
77. Urtica (Urticaceae) 'Stinging nettle'
This generic name comes from the Latin, uro, meaning to burn or sting. The obvious way to recognize a nettle is not recommended! In the past nettles have been used for a wide variety of purposes, from making rope to curing arthritis. The flowers are wind pollinated and therefore not visited by insects, nevertheless over 50 species of insects, such as beetles, aphids, flies, butterfly and caterpillar moths, have been known to eat the leaves.

78. Salix (Salicaceae) 'Willow'
Individual species in this often-hybridizing genus can be difficult to tell apart. Anybody up to becoming an expert? Be sure to collect both the male and female plants if you collect these species. The compound used for making the pain killer aspirin (salicylic acid) was originally derived from the bark of this family. Native Americans and early settlers would chew on it to relieve pain. The leaves do have a distinctive shape and often have large stipules. If you ever see a "cone" growing on a willow you have found an insect gall.

79. Parthenocissus (Vitaceae) 'Virginia creeper'
The Latin for this genus name can be roughly translated as “immaculate conception.” One trick you might use to remember both the Latin name and the common name is to note that both of the plant’s names (common and Latin) and the state (Virginia) are named after the Virgin queen of England. The species are vines that climb with the adhesive disks at the ends of their branched tendrils. The 5-lobed leaves turn a spectacular red and wine color in the autumn.

80. Vitis ( Vitaceae) Wild grape'
Vitis is one of only a few native genera (along with Parthenocissus) that you will see in Wisconsin that are lianas. If you are not sure about the definition of this term, ask Tarzan whether he swung on vines or lianas? There are only two species of Vitis native to Wisconsin, however other species and varieties are grown across the state. .