Lab 19: Spiderworts,Sedges and Grasses

 

Go to last lab (Petaloid monocots) Go to lab syllabus


Introduction: This last lab comprises the majority of the graminoids. The term 'graminoids' refers to the monocot life form that entails narrow, ribbon-shaped (or finer) leaves and generally inconspicuous, predominantly wind-pollinated flowers. All in this order are relatively closely related. They can be difficult to tell apart, especially those in the first three families. Familiarize yourself with all bold-faced terms. Refer to pages the Lecture handouts for illustrations.


Poaceae, the grass family ( = Gramineae)
Diagnostic family characteristics:
- Leaves flat or involute, 2-ranked.
- Leaf sheaths generally open, with a ligule that is loose from the leaf blade.
- Flowers bisexual and arranged in a characteristic inflorescence referred to as a spikelet, composed of two outer glumes subtending one or more florets. Each floret comprises two bracts, an outer lemma and an inner palea.
- Fruit is a grain, or karyopsis.

Examine the spikelet of Avena sativa (oats) set up as a demonstration on the front table and find these parts.

The grasses are one the world's largest and best studied families of angiosperms. Important as forage and human food, even used in construction (bamboo), the grasses are perhaps the fittingest family with which to cap off our Vascular Flora of Wisconsin experience!

161: Dichanthelium 'Panic grass'
This genus of small grasses is easy to recognize but the species are very hard to tell apart. The species bloom in spring and then again in the fall, taking on a very different habit. Most species are found in prairies and are often hairy.

162. Dactylis 'Orchard grass'
This exotic grass is found in all kinds of disturbed habitats and is an early bloomer. The inflorescence often has a small side branch below the “main” cluster of spikelets.

163. Phalaris arundinacea 'Reed canary grass'
This grass has both native and non-native strains in the U.S. The non-native strains are highly invasive and have destroyed many acres of wetlands across the state. There are many marshes around Madison that are dominated by this grass. The tawny-colored inflorescences are densely packed and allow for identification, even from far away.


Cyperaceae, the sedge family
Diagnostic family characteristics:
- Leaves flat, involute, or obsolete, 3-ranked.
- Leaf sheaths closed, often with a ligule that is adnate to the leaf blade. Sides of the sheath are referred to as the ventral sheath and the dorsal sheath (front and back respectively).
- Flowers unisexual or bisexual, each subtended by a single bract. In the genus Carex, a perigynium completely encloses the female flower and serves as the dispersal unit.
- Fruit an achene.

One of the world's largest genera is in this family, the genus Carex, with roughly 2,000 species worldwide. It is traditionally divided into three or four subgenera, two of which occur in Wisconsin:


 

 subgenus Vignea

 subgenus Carex

 Stigmas

 2

3 (2 in a few sections)

 Spikelets

bisexual, all alike, sessile

unisexual or predominantly so, rarely sessile

Achenes

lenticular

triangular or terete in cross section
(lenticular in a few sections)


You can learn Carex in Wisconsin using Andrew Hipp’s (a former TA of this course) Field Guide to Wisconsin Sedges.

Key out species 164: Carex lacustris 'Lake sedge'. Subgenus Carex.

165. Schoenoplectus tabernaemontani 'Soft-stem bulrush' (= Scirpus validus)
This sedge grows up to 2 meters with stems up to 1 cm in diameter. It spreads via rhizomes and grows in both fresh and brackish water. Defined broadly, the species is widespread worldwide. Keep in mind that plants commonly called 'bulrushes' are sedges (Cyperaceae) and not rushes (Juncaceae). Generic and specific circumscription is in flux in this genus. This species can be very difficult to distinguish from the hard-stem bulrush, S. acutus. The two are said to hybridize readily and may frequently grow near one another.

Species to learn:

166. Dioscorea villosa 'Wild yam,' 'Colic-root' (Dioscoreaceae)
In our flora, this species bears similarity to the genus Smilax. Wild-yam, however, has cordate leaf bases. The species is found growing in wet woods, swamps, and thickets from New England all the way to Texas. The root, harvested in September, was traditionally used to make a homeopathic remedy for infant colic. Today, it is widely used in modern medicine in the manufacture of progesterone and other steroid drugs. The roots contain a precursor of progesterone, making it a popular choice for treating PMS. Keep in mind that eating the fresh plant can cause vomiting and other side effects.

167. Tradescantia ohiensis 'Common spiderwort' (Commelinaceae)
This perennial native of eastern North American prairies and open oak woodlands bears blue, purple, pink, or white flowers from May to July and can reach a height of up to 24 inches in the wild and twice that much in your garden with fertilizer. The flowers play "peek-a-boo;" they open up first thing in the morning and then close again by early afternoon. Stems and leaves are glaucous silver, grey or bluish, and the plant is topped with "spidery" clusters of bright colors.

Genera to learn:

168. Smilax 'Carrion flower,' 'Greenbriar' (Smilaceae)
All but one of our species of this genus have tendrils. Be able to tell this genus from Dioscorea. Smilax is a perennial species that thrives in wooded or thickened areas. It is characterized by thick, tough stems and waxy, heart or arrow shaped leaves. However, the most noticeable feature are the numerous thorns that are found along the stems and leaves (in certain species) of Smilax. It produces small, inconspicuous flowers and berry-like fruit. These fruits are readily eaten by birds, which are the primary means of dispersal.

169. Typha 'Cattail' (Typhaceae)
This tall perennial herb is characterized by a creeping rootstock; long, flat leaves; flowers in a dense cylindrical terminal spikes; and brown, cylindrical fruits with a velvety surface. They grow in freshwater swamps in both temperate and tropical regions. Native Americans had numerous uses for cattails, they made a type of flour out of the roots and made numerous things from baskets to wigwams out of the leaves. In WI the only species are: Typha latifolia (wide leaves), Typha angustifolia (narrow leaves), and a hybrid between the two, Typha X glauca.

170. Juncus 'path rush' (Jucaceae)
The rush family is a graminoid like grasses and sedges. Rushes differ in having bisexual flowers with six small, scale-like tepals, and multi-seeded capsules. They can be found in forests or open areas, wet or dry.