My Continuing Journey to Learn How to Identify Grasses

My Continuing Journey to Learn How to Identify Grasses
(article originally for the Elm Fork Chapter Master Naturalist newsletter)by Jeanne Erickson
Recently a friend watched the NPSOT presentation that Brain Loflin made on Grasses of the Texas Hill Country and she emailed me to ask what I thought of their 2006 book of the same name. I have had the Loflin book for several years now and it does a good job in the text describing many unique physical details of the grasses included which are well supported by the photos. Its organization by inflorescence form is unique and really forces one to look closely at the inflorescence and pick it apart as it is not often immediately apparent what the floral structure of the grass actually is. I must admit that after I bought the book I did not make a concerted effort to learn how to best utilize it – at that I was time simply looking for books with photos that would help in the identification of grasses - I didn’t really study.

For many years I had been wishing that someone someday would conduct a serious class on how to ID grasses, but eventually I realized that it would need to be an entire semester! Attending presentations and workshops on grass identification were very helpful and one can get good tips from the presenters, but due to the time constraint they can really only include a brief high level overview. Hands-on learning by going out with knowledgeable people on field trips or work projects was (and still is) a great way to learn how to identify and see the habitat of the most common grasses as well as some of the less common but distinctive ones too. A 10x–20x magnifying loupe is recommended for looking at details more closely. In both cases, multiple experiences are recommended – there is so much to learn!

Another challenge is that for the most part, the details of the inflorescence are used to arrive at the identification. Frequently details of the roots and vegetative parts may be used to distinguish between species within a genus (so collecting the entire plant with some roots attached is highly recommended), but generally, as in keying other plants, the floral parts are required. So one must often wait for grasses to be in bloom to go looking and collecting. So far, my identification activities have been limited to collecting grasses in bloom and not saving them in any sort of private “herbarium” for later reference. The disadvantage of this is that study becomes a seasonal event and between seasons forgetting what one has already worked through is distinct possibility.

Luckily, many of the most widespread and important grasses have distinctive vegetative parts that can be used for identification most times of the year. These include little bluestem, big bluestem, Indian grass, hairy grama, threeawns, switch grass and sideoats grama.

A recent an on-line search for publications that have keys for identification of grasses using only vegetative characteristics yielded a few possibilities, so the next challenge is to try those out. Most are regional, some are quite old. They are listed at the end of this article.

As with anything else, what you would like to do and what books you acquire to assist in that effort are dependent on how deeply you want to educate yourself in the identification of grasses. My goal has been to identify all the grasses at my property and other places that I visit, so I needed to do something more intensive and on my own as there are simply no comprehensive grass identification classes available in our area. Learning the most common major grasses is not very hard – most are pretty distinctive and the picture books and the field trips and collecting on your own really help with that. It is learning to identify all the other not-so-common grasses that can be the bigger challenge.

My self-study went like this:

During the wintertime:

Studied the entire book: First Book of Grasses, Agnes Chase, 1902, updated 1959, 152 pages – not a key; a great little book that I reference frequently.
Studied the Introduction and perused the rest: Field Guide to Common Texas Grasses, Stephan Hatch, 2016, 323 pages – has a key, drawings and photos as well as good descriptions of all the plant parts. If I carry one book out in the field, this is it.

Studied Chapter 2 and the picture key and perused the rest: Guide to Texas Grasses, Robert Shaw, 2012, 1080 pages – has a great key that illustrates the grass flowers on the opposite page which is very helpful; drawings and photos, individual descriptions not as detailed as in Hatch.

In the Spring I bought a dissecting microscope and just started looking closely and taking things apart. I created a detailed checklist to use during the process to make sure I looked at all the details; it has been recently revised to include an area for sketches to better allow it to serve as a “paper herbarium” and help with recall of those specimens keyed in the past. It was frustrating at first due to all the new nomenclature and terms to learn as well as figuring out exactly what to look for and how to recognize the diversity of floral structures. This was complicated by the fact that some grasses are actually missing some of the usual parts (that is where the Agnes Chase book really helped), but I was able to slowly but surely make headway. Some of the grasses still elude me in the keying process, but I keep trying. It did not help that I had no previous experience in using a dichotomous key to identify anything before, not even wildflowers.

The Hatch and Shaw books have the keys I use for identification work. I start with Hatch, and then go to Shaw if not found in Hatch, then compare both for review. Both use detailed line drawings and photos to illustrate the grasses. For those years when I was simply collecting picture books of grasses, I did not understand how useful those drawings are for identification, but after using the books and keys and really looking closely, I realized that they are indispensable. The drawings highlight the minute details of the plants and flowers required for identification, especially for the species that are quite similar within a genus.

But all that winter reading and study really did help. And looking through a loupe and microscope and taking things apart is FUN. One just has to decide to start!

Books on grasses included my library:

Grasses of Texas, Frank Gould, 1975, Texas A&M University Press,  653 pages – this book is a particularly useful resource as it lists and describes all the details of every grass which allows one to compare them with grasses that are similar and understand the small differences between them. Highly recommended. The shorter version, “Common Texas Grasses”, is not recommended as it does not have a complete list of Texas grasses.

Grasses of Southern Oklahoma and North Texas: A Pictorial Guide, Chuck Coffey & Russell Stephens, 2004, Samuel Roberts Noble Foundation, 120 pages – a great picture book with photos of plant details that is unfortunately out of print. I did not see that it is available on-line – maybe the Noble Research Institute can help.

Grasses of the Texas Hill Country, Brian & Shirley Loflin, 2006, Texas A&M University Press, 195 pages – grasses are arranged by structural similarity of the grass seedhead, not by genus; includes full page photos of the seedhead and usually a smaller photo of entire plant, full page description of features, uses, habitat and growing season; the focus is on the nineteen West Central Texas counties known as  “Texas Hill Country”, but most of the grasses included can be found in North Central Texas.

Range Plants of North Central Texas, Ricky J. Linex, 2014, NRCS, 345 pages – the grasses section (pages 163-222) has photos and very good descriptions of the most common grasses as well as their wildlife value, use and management.

How to Identify Grasses & Grasslike Plants, H. D. Harrington, 1977, Swallow Press, 154 pages – describes and illustrates the parts of grasses in sequence using small, simple line drawings, includes an illustrated glossary and a section on sedges and rushes as well as a short chapter on identification of grasses when they are not flowering.

Texas Range Plants, Stephan Hatch and Jennifer Pluhar, 1993, Texas A&M University Press, 326 pages – 73 grasses included on pages 30-177 each with a full page drawing and full page description, no key.

Know Your Grasses, Barron Rector, 015, Texas Cooperative Extension, publication B-182 – 81 grasses with drawings and descriptions.

Grass Systematics, Frank Gould and Robert Shaw, 2000, Second edition, Texas A&M University Press, 412 pages – originally designed to serve as a guide, textbook and source of information for undergraduate courses in agrostology; not a key or identification guide.

Glossary of terms:

How to Identify Grasses & Grasslike Plants, Harrington – noted above
Plant Identification Terminology – An Illustrated Glossary, James G. Harris & Melinda Wolf Harris, 2001, Second edition, Spring Lake Publishing, 206 pages – lots of drawings; terms for use in plant taxonomy; recommended by BRIT.

On-line resource:

Flora of North America, Poaceae, Volumes 24 & 25,, includes descriptions, keys and distribution maps as well as illustrations of grass species in North America.

Identification of Grasses by Their Vegetative Characteristics found on-line and listed by date:

The Identification of Grasses by Their Vegetative Characteristics, Lyman Carrier, 1917, USDA Bulletin No. 461, 32 pages – 56 species including 13 grains

The Identification of Certain Native & Naturalized Grasses by Their Vegetative Characters, R. F. Copple & A. E. Aldous, 1932, Agricultural Experiment Station, Kansas State College of Agriculture and Applied Science – 72 pages – 26 species

The Identification of Certain Native & Naturalized Hay & Pasture Grasses by Their Vegetative Characters, F. S. Nowosad, D. E. Newton Swales, W. G. Dore, 1936, MacDonald College, McGill University, Technical Bulletin No. 16 – 84 pages, 38 plates (sketch & detailed descriptions); appendix w/ drawings of sections of Poa, Carex, Juncus leaves

The Identification of Some of the More Common Native Oklahoma Grasses by Vegetative Characters, William Franklin Harris – Master of Science Thesis, Published by Oklahoma Native Plant Record, Volume 10, December 2010 – 29 pages – 50 species

A Vegetative Key to the Grasses of Erath County, Texas, Inez Evans Robinson – Master of Science Thesis, 1951, North Texas State College #193392 – 48 pages – 74 species listed, 86 specimens examined, 100 figures
Key to the Native Perennial Grasses – Midwest Region East of the Great Plains, Abstracted from Hitchcock’s Manual of the Grasses, 1968, USDA Soil Conservation Service SCS-TP-151, Washington, DC, – 124 pages

A Field Guide and Key to Fifteen Grass Seedlings, Mary Hockenberry Meyer & Virginia Gaynor, 2000, Department of Horticultural Sciences, University of Minnesota, J. Nat. Resource. Life Sci. Educ. 29:141-147 (2000) -7 pages – 15 species

Grasses of the Texas Hill Country: Vegetative Key and Descriptions, Karl W. Hagenbuch & David E. Lemke, 2015, Phytoneuron 2015-4: 1-93. 7 January 2015. ISSN 2153 733X – 93 pages – 66 genera 160 species; this one has very good sketches