The plant world can often date or age me, and this species is no exception. I learned about Mexican feather grass as Stipa tenuissima, a scientific name still used by the nursery trade and others that refuse to follow the science. Maybe a refusal is a little harsh, since it means changing labels, websites, and books for an update. The latest edition of what locals call the "garden bible," The New Western Sunset Western Garden Book as of 2012 has not republished and still lists this plant as a Stipa (p. 614). As for me, when my informative years taught me about Stipas, my old brain clings to the past. Plant names often evolve as scientist learn more about the plants, right down to their genetic make up, whereas early botanist went by observing characteristics. Anyway, not wanting change is my only excuse, but writing this post is helping me get with the program. Nassella tenuissima it is!
The grass blades are thin and fine textured, and when it blooms, its inflorescence are even finer. The first photo below is a project I designed for a corporate headquarters, a mound of Mexican feather grass eluding to the grassy, rolling hillsides of California. When the wind blew, its movement was mesmerizing, making the mound a subtle kinetic land art. It lasted for quite a while (note to self to see if it is still there), but maintenance, if not done right, can damage its performance.
N. tenuissima is hardier than it looks, providing it receives proper care and is not overwatered. One of the major concerns is when and how to prune after bloom. Leaving spent inflorescence on too long, and the plant will become weighed down affecting its ability to photosynthesize. The inflorescence can get matted together, further making it unsightly. This is also the time when plants can easily reseed themselves, which might not be desirable in other parts of the landscape. Note that the California Invasive Plant Council deems it one to watch for its invasiveness. Cutting the plant too short and at the wrong time of year may result in either sun scorch (summer) or rot (winter). If maintenance challenges can be resolved (including reseeding prevention), N. tenuissima is a worthy and unique texture in the ornamental garden.
facts
Botanical Name: Nassella tenuissima
Nassella: Latin for nasus or nassa, or "basket with narrow neck," that according to the Missouri Botanical Garden was used for fishing. The form describes how the lemmas overlap, a part of the inflorescence structure.
Tenuissima: Slender or thin
Common Name: Mexican feather grass
Family Name: Poaceae
Origin: Mexican, New Mexico, Texas
design considerations
Positioning: Foreground, container, embankment
Garden Themes: Drought, rock, children's, meadow
Uses: Slope, small spaces/courtyard/patio, container/planter, mass, erosion control
identifying characteristics
Type: Semi-evergreen grass
Form: Upright, arching, clumping
Texture: Fine
Size: 2' tall by 3' wide at peak bloom
Outstanding Feature(s): Texture
Bark: N/A
Leaf:
Type: Simple
Arrangement: Alternate
Shape: Linear
Margin: Entire
Color: Light green
Surface: Directional barb
Flower: Spring to Autumn. Inflorescence catkin, fine textured, showy, golden yellow turning pale with age.
Fruit: Autumn. Inconspicuous tan caryopsis (easily reseeds)
cultural requirements, tolerances & problems
Sunset Zones: 2b-24
USDA Zones: 5-10
Light: Sun to partial shade
WUCOLS SF Bay Area Hydro Zone: Low
Soil:
Texture: Sand, loam, clay
Moisture Retention: Well-drained; moist to very dry
pH: Lightly acidic to lightly alkaline
Tolerances: Drought, erosion, deer
Problems: Invasive in certain areas
Branch Strength: N/A
Insects: Not recorded as of this post
Disease: Not recorded as of this post
citations & attributions
Bayton, R. (2019). The Royal Horticultural Society's the Gardener's Botanical: An Encyclopedia of Latin Plant Names. London: Mitchell Beazley.
Extension Gardener. "Nassella tenuissima." North Carolina State University, Raleigh. Accessed on August 21, 2021 from https://plants.ces.ncsu.edu/plants/nassella-tenuissima/.
Norris Brenzel, K. (Ed.). (2012). The New Sunset Western Garden Book. New York: Time Home Entertainment, Inc.
Plant Finder. "Nassella tenuissima." Missouri Botanical Garden, St. Louis. Accessed on August 21, 2021, from http://www.missouribotanicalgarden.org/PlantFinder/PlantFinderDetails.aspx?taxonid=285344.
Plants A to Z. "Stipa tenuissima." California Invasive Plant Council, Berkeley. Accessed on August 21, 2021 from https://www.cal-ipc.org/plants/profile/stipa-tenuissima-profile/.
Taxon Report. "Nassella tenuissima." Calflora, Berkeley. Accessed on August 21, 2021, from https://www.calflora.org/app/taxon?crn=8685.
Water Use Classification of Landscape Species. "WUCOLS IV Plant List." University of California, Division of Agriculture and Natural Resources, Davis. Accessed on August 21, 2021, from
Photos:
Leading photo: "Stipa (Nassella) tenuissima - Mexican feathergrass" by Matt Lavin is licensed under flickr.
All other photos by TELCS.