Dichotomous Key

My time here in the great basin has been full of new experiences. One of these new experiences has been creating a simple dichotomous key focused on riparian areas. I have been working on these keys with some of my fellow interns. The dichotomous keys that we create will be used in a Native American youth camp that we will have the pleasure of assisting with in a few months. The youth camp is going to be with high school aged students which creates a scope of challenges. The key needs to entertain the kids as well as inform them. As we all know dichotomous keys can be complex and at times hard to follow.  We are trying to avoid that hardship, especially with grasses. The keys also need to be short because the students will be working on identifying these plants within a small block of time in a field setting. My team mate Andrii and I have come up with this preliminary key:

Grasses, Sedges and Junceae

1a Plants have a triangular stem with parallel veined leaves up to 1″ wide; stems are round to oval with leaves extending from the base; inflorescence is found on the stem

    2a Stem is roughly triangular with flat leaf blades. Inflorescence is at the tip of the plant extending from multiple branches that have fruit like seeds surrounded by scales; fruit length is approximately 0.7-1.6mm. Scirpus microcarpus

     2b Stem is oval to round with leaves extending from the base of the plant. Inflorescence is found on the stem.

          3a Leaf blades flat and broad, some have rolled edges. Inflorescence is cylindrical found at the top of the plant, appearing like a large speared hotdog.  Fruit is like a seed surrounded by hairs.  Typha latifolia

3b Leaves are basal, bladeless sheaths. Inflorescence is found on the side of the stem, not at the terminal end. Flowers are small, dark and brown. Juncaceae Juncus balticus (articus)

1b Plants differ in size and appearance  (never triangular). Usually  have hollow stems and swollen leaf nodes. Cauline (on the stem) leaf consists of a tubular sheath  on the lower portion and a free narrow leaf blade; basal leaves often form dense tufts, a combination of both types is very common.   Poaceae; true grasses

     4a Plants that are very tall – 7-14’, rhizomous. Leaves are alternate  along the stem; leaf blades are about 1’ long and up to 2″ wide.  Panicle is open, sometimes reddish in color. Plants tend to form very dense stands, occupying moist to wet areas of riparian zones. Phragmites australis (common reed)

     4b Plants that are much smaller.

5a Inflorescence is dense and compact; spikelets are sessile or sit on very short pedicels

6a Plants are annual, up to 8” tall. Awns are densely arranged, 5-9 mm long. Leaf blades are flat, glabrous; ligules are membranous 5-6.3 mm long. Can be found in riparian zones and disturbed areas. Polypodium mospeliensis (rabbitfoot beardgrass)

6b Plants that are perennial, usually taller.

7a Grass grows in tufts, with culms about 4-25” tall. Awns are loose, 1-4” long and are widely divergent in maturity. Leaves 1-6 mm wide, can be flat or involute; collars usually yellow with 0.4-0.6 mm membranous ligules. Plant can grow in a broad range of soils and is valuable forage for large animals. Elymus elymoides (bottlebrush squirreltail)

7b Awns are shorter or absent.

8a Glumes are narrow, needlelike. Ligules are always membranous, but well distinctive – 1-8 mm long. Leaf blades are flat, scaberulose and glabrous. Plants are common mainly along streams, or in dryer sites of riparian zones. Leymus cyneresus ( basin wildrye)

 8b Ligules are absent or very short.

9a Plants are perennial and tufted. Culms are up to 3’ tall,  spikes are no longer than 6”. Spikelets are awned. Leaves are long, involute and coarsely veined. Collars can be yellowish in color, usually with short 1 mm long ligules. Commonly grows on dry, rocky hill sides or plains. Pseudoroegneria spicata (bluebunch wheatgrass)

9b Perennial and tufted grass. Spikes are shorter –1-2.5” long. Leaves can vary from flat to involute, collars are often yellowish with 0.3-0.7 mm long ligules. Can be found on grazing areas, disturbed lands like roadsides and burned areas. Agropyron cristatum( crested wheatgrass)

5b Inflorescence is open, can be narrow but spikelets are on distinctive pedicels

10a Plants are annual. Culms are usually 2’ tall with relatively large, drooping and awned spikelets. Leaves are slightly haired. Plants can occupy a wide range of habitats, from uplands to riparian zones. Bromus tectorum(cheatgrass)

10b Plants are not alike. How are the plants not alike, not like the above plants or not like each other?

11a Inflorescence is diffuse with distinctive branchlets. Spikelets have one flower and dark seed when mature. They can commonly be found in sandy, clayey and well drained soils throughout the Great Basin.  Oryzopsis hymenoides (Indian Ricegrass)

11b Inflorescence is narrow to diffuse. Spikelets are awnless but bear many flowers. Poa; (bluegrass)

12a Plants are rhizomatous and usually don’t form dense tufts. Panicle is often pyramidal, about 2-6” long. Leaves are flat or folded with 0.4-0.6 mm long ligules. Commonly foundon moderately dry roadsides, meadows and open woods.  Poa pratensis; (Kentucky bluegrass)

12b Small, densely tufted perennials. Spikes are 1.5-3.5” long. Leaf blades are soft, folded or involute, often boatshaped at a tip. Ligules are membranous, about 1.7-5 mm long. Commonly grow in relatively dry habitats, sagebrush valleys, and wooded areas. Poa secunda (Sandberg bluegrass )



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