Distinguishing Yellow Trout Lilies in E USA

It's easy to distinguish our three yellow trout lilies from one another when they are in-fruit, or dug-up. But what about when they're in-bloom? You know, when you notice them?

The presence of stolons can be inferred from the number of one-leaved, 'sterile' plants in a population. The stolon-producing species often produce carpets of plants in this stage; E. umbilicatum subsp. umbilicatum will only produce the occasional cluster of steriles, which are either same-aged siblings (clustered by a single fruit dispersal event) or offsets with the blooming-sized parent eaten/missing.

Clifford Parks and James Hardin (1963) carried out an exhaustive study of their floral characteristics and correlated them to stolon production, ploidy, and capsule shape. I thought the results of their paper might be useful to iNaturalists. They are summarized here:

E. rostratum E. americanum E. umbilicatum
subsp. umbilicatum
E. umbilicatum
subsp. monostolum
tepal carriage agape strongly reflexed strongly reflexed strongly reflexed
flower angle erect nodding nodding nodding
stolons 1+ 1+ 0 1
capsule shape
in profile
strongly beaked
rounded, truncate,
or apiculate
rarely merely truncate
capsule presentation held erect not erect
but still held off the ground
reclining on the ground reclining on the ground
or rarely just above
petal bases clearly auricled
encircling filaments
minutely auricled
or toothed
not auricled not auricled,
but margin irregular
green coloration
on abaxial side of tepals
none none or slight none present
pale spot
at base of inside of tepals
absent absent in 90%
otherwise vague or small
always present,
but sometimes small
always present
often prominent and large
dark flecking
on perianth
absent absent or slight absent or slight,
but variable
always present,
few to many
style thickness
just below point of
stigmatic divergence
thickened thickened remains thin remains thin
stigma lobes swollen
anther & pollen color yellow
or brown-lavender
rarely yellow
rarely yellow
ploidy diploid tetraploid diploid diploid

Not included: E. americanum subsp. harperi, because the authors questioned its distinctiveness. It's mainly distinguished from E. americanum subsp. americanum by having (1) more strongly-apiculate capsules and (2) stigma lobes that are 'distinctly grooved distally' and variously described as 'recurved' or merely 'divergent'. It is documented from Alabama, Georgia, Mississippi, and southern Tennessee. Geraldine Allen and Kenneth Robertson consider it to be more reliably distinct and single it out in their treatment of the genus for The Flora of North America entry.

Posted on February 21, 2018 09:28 PM by ddennism ddennism


Great chart! We have a few Erythronium species here in TX, and there's some... discussion... on how to tell a few apart.

Posted by sambiology about 5 years ago (Flag)

@sambiology - thanks, it's not really my own work, just a reproduction and summary from a paper. I assume you're talking about E. albidumand E. mesochoreum in Texas? You know, hybrids between those two are not unheard of, even though the two remain largely in reproductive isolation.

Posted by ddennism about 5 years ago (Flag)

I've really struggled on telling Erythronium albidum from E. mesochoreum in Texas... I've had folks explain it to me, but something about it -- I just don't see the differences! :-/ And hybridization just throws another fun curve ball in there! :)

Posted by sambiology about 5 years ago (Flag)

Thanks so much for the chart- I think you’re correct! - Julia

Posted by jhuffj almost 3 years ago (Flag)

This is excellent. Thank you for sharing your research

Posted by ecoria 12 months ago (Flag)

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