A new paper identifies 65 plant extinctions in the continental United States and Canada — but that’s probably just a fraction of what we’ve lost.

Franklin tree

The Caddo false foxglove. The pale bugseed. The largeleaf leather-root.

These are just a few of the plant species and varieties that have gone extinct in the continental United States and Canada since the beginning of European colonization.

A new paper documents 65 such plant extinctions — five small trees, eight shrubs, 37 perennial herbs and 15 annual herbs — the losses of most of which have never been reported before. Most of these species had limited ranges or were known from single sites, and likely went extinct following the destruction of their habitats. A few were lost due to dams, invasive species or overgrazing.

This new record of what we’ve lost contains 51 species and 14 varieties. These variants, or “infraspecific taxa,” as the paper calls them, may not have been full species, but they still contained unique and potentially important genetic traits.

The list includes a three-foot-tall daisy called Marshallia grandiflora, which some of the same authors declared extinct earlier this year.

It also includes seven plants that are now considered “extinct in the wild,” meaning they only exist in botanical gardens. Four of those “extinct in the wild” plants were, until this paper, thought to still be living in the wild. The evidence now suggests that three trees from the hawthorn family — Crataegus delawarensis, C. fecunda and C. lanuginose — and a bittersweet shrub variety called Euonymus atropurpureus var. cheatumii have narrowly avoided extinction due to their cultivation in botanical gardens.

“I was astonished,” says biologist Wesley Knapp of the North Carolina Natural Heritage Program, the lead author of the new paper. “The fact that botanical gardens had the last known living material of a species, yet they were unaware of this, was shocking and it’s spurring future work. Unfortunately for some species, there is little hope aside from a future in gardens or seedbanks. This is certainly better than extinction.”

Losing 65 species and varieties is bad enough, but, as the paper also warns, the continent has probably experienced a much higher level of extinction than could ever be catalogued or assessed. That’s because Europeans settlers typically moved into new areas, particularly the American West, before scientists could document the species that lived there. If those species had small ranges, the authors write, they could have easily disappeared due to agriculture and other development before they were identified or named by scientists.

Of the extinctions that researchers could catalog, 19 came from California, nine from Texas and five from New England. Only one extinct plant on the list came from Canada — suggesting more of a knowledge gap or a research opportunity than necessarily a better conservation record. “It is highly unlikely that New England would have seen five extinctions but adjacent parts of Canada zero. I suspect this is all an artifact of our knowledge — or lack of,” says Knapp.

As bad as this news is, the authors caution that most of these losses should be considered “presumed extinctions.” Even though many species have not been seen for decades, they could reemerge if people look long and hard enough.

“Surprises happen,” says Knapp. He points to this year’s rediscovery of a grass subspecies called Sphenopholis interrupta californica — which was found in California after previously being known from two sites in Mexico — and the famous case of the Wollemi pine (Wollemia nobilis), which was known only from fossil records before it was found alive in Australia in 1995.

“Even plants not seen for millions of years, or plants completely new to a geographic area where they have not been seen before, can be found,” he says. “I hope every plant on this list is ultimately rediscovered. Drawing attention to them is the best way to possibly help spur their rediscovery.”

And the paper may serve as incentive to find and save other plant species, especially ones that have been sparsely documented in the scientific literature, or species without known living specimens available for genetic testing.

To assist in these types of efforts, the authors developed what they call the “Index of Taxonomic Uncertainty,” a new methodology that ranks species based on how often they’ve been studied. The rarer the study, the lower the level of certainty about whether the plants truly represent species, subspecies or variants, or if even if they still exist. The paper’s supplements contain rankings on more than 400 such plants, about 150 of which have rarely been seen or never catalogued after their initial scientific description.

Knapp says this system, or others like it, may help to reassess rarely seen species or inspire efforts to fill scientific gaps about little-known plants. “Our knowledge is ever-changing,” he says.

That’s reflected in the paper itself, which in earlier drafts projected 53 species extinctions, not the published 51. One of the species was moved to the variety list during peer review, Knapp says.

As to the other? Well, Knapp says recent reports suggest an assumed-lost species of hollyhock could represent another possible rediscovery — proof that hope remains and that we should never give up looking for species we may have lost.

The full list of extinct plant species appears below:

Taxonomic name Common name (if known)
Agalinis caddoensis Caddo false foxglove
Arctostaphylos franciscana Franciscan manzanita
Astilbe crenatiloba  Roan Mountain false goat’s beard
Astragalus endopterus Sandbar milkvetch
Astragalus kentrophyta var. douglasii Barneby Douglas’ thistle milkvetch
Astragalus robbinsii var. robbinsii Robbins’ milkvetch
Atriplex tularensis Bakersfield smallscale, Tulare saltbush or Tulare orach
Blephilia hirsuta var. glabrata Hairy wood-mint
Boechera fructicosa 
Brickellia chenopodina Chenopod brickellbush
Brickellia hinckleyi Standley var. terlinguensis
Calochortus indecorus Sexton Mountain mariposa lily
Calochortus monanthus Single-flowered mariposa lily or Shasta River mariposa lily
Calystegia sepium binghamiae Bingham’s false bindweed
Castilleja leschkeana Point Reyes paintbrush
Castilleja uliginosa Pitkin Marsh Indian paintbrush
Cirsium praeteriens Palo Alto thistle
Corispermum pallidum Mosyakin pale bugseed
Crataegus austromontana Valley Head hawthorn
Crataegus delawarensis
Crataegus fecunda St. Clair or fecund hawthorn
Crataegus lanuginose Woolly hawthorn
Cryptantha aperta Grand Junction cryptantha
Cryptantha hooveri Hoover’s cryptantha
Cryptantha insolita Las Vegas cryptantha
Dalea sabinalis Sabinal prairie clover
Digitaria filiformis var. laeviglumis Slender crabgrass
Diplacus traskiae Mimulus traskiae
Eleocharis brachycarpa Shortfruit spikerush
Elodea schweinitzii Schwe initz’s waterweed
Erigeron mariposanus Foothill fleabane, Mariposa daisy or Mariposa erigeron
Eriochloa michauxii var. simpsonii Simpson’s cupgrass
Euonymus atropurpureus var. cheatumii (extinct in the wild) Eastern wahoo
Franklinia alatamaha Franklin tree
Govenia floridana Gowen’s orchid
Hedeoma pilosa Old blue false pennyroyal
Helianthus nuttallii parishii Los Angeles sunflower or Parish’s sunflower
Helianthus praetermissus Lost sunflower
Isocoma humilis Zion goldenbush or Zion jimmyweed
Juncus pervetus Blunt-flower rush
Lechea lakelae Lakela’s pinweed
Lycium verrucosum San Nicholas desert thorn or San Nicolas island desert thorn
Marshallia grandiflora Barbara’s buttons
Micranthemum micranthemoides Pearl weed
Monardella leucocephala
Monardella pringlei Pringle’s monardella
Narthecium montanum Appalachian yellow asphodel
Orbexilum macrophyllum Largeleaf leather-root
Orbexilum stipulatum  Largestipule leather-root or Falls-of-the-Ohio scurfpea
Paronychia maccartii McCart’s nailwort
Plagiobothrys lamprocarpus Shiny-fruited allocarya
Plagiobothrys lithocaryus Mayacamas popcorn flower
Plagiobothrys mollis var. vestitus Petaluma popcorn flower
Polygonatum biflorum var. melleum Smooth Solomon’s seal
Potentilla multijuga Ballona or lost cinquefoil
Potentilla uliginosa Cunningham marsh cinquefoil
Proboscidea spicata New Mexico unicorn-plant
Prunus maritima var. gravesii
Quercus tardifolia Chisos Mountains oak or lateleaf oak
Ribes divaricatum var. parishii Straggly gooseberry
Rumex tomentellus Mogollon dock
Sesuvium trianthemoides Texas sea-purslane
Sphaeralcea procera Porter’s globe mallow
Tephrosia angustissima var. angustissima Coral hoary pea
Thismia americana Thismia or banded Trinity

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John R. Platt

is the editor of The Revelator. An award-winning environmental journalist, his work has appeared in Scientific American, Audubon, Motherboard, and numerous other magazines and publications. His “Extinction Countdown” column has run continuously since 2004 and has covered news and science related to more than 1,000 endangered species. He is a member of the Society of Environmental Journalists and the National Association of Science Writers. John lives on the outskirts of Portland, Ore., where he finds himself surrounded by animals and cartoonists.