Wednesday, January 21, 2015

Trillium cernuum and Trillium flexipes

Often confused with the similar Trillium flexipes, the first two photos below are Trillium cernuum.  Look closely at the stamens... the anthers and filaments are approximately the same length.  In Trillium flexipes, the anthers are much longer than the filaments.  The ranges of the two species sometimes overlap, but Trillium cernuum is generally a more northern species, whereas Trillium flexipes is generally more southern. 
 


The photos above are from Bog Meadow Nature Trail in Saratoga County, New York, May 21, 2014.

For comparison, here are four photos of Trillium flexipes. The first was taken at Turkey Run State Park, Parke County, Indiana, May 3, 2008.  The next three were taken at Bendix Woods Nature Preserve, St. Joseph County, Indiana - the first two on May 5, 2013 and the last on April 25, 2009.  Again, take a close look at the anther to filament ratio. The anthers are much longer than the filaments in Trillium flexipes





I tend to think that the anther to filament ratio is a better way to distinguish these two similar species than the actual length of the filaments.  Many references use a filament length of up to 2 or 2.5 mm for Trillium flexipes in their keys, but if you dissect the flower you often can find filaments that are longer than 2.5 mm.  In fact, I would be willing to bet that the filaments in the first through third photos of Trillium flexipes above have filaments longer than 2.5 mm (I can see them pretty easily without even dissecting the flowers). 

All of this said, I have seen specimens in northern Indiana that are somewhat intermediate between the two species, so the distinctions are not always as black-and-white as they are in these photos.

12 comments:

Pete said...

I thought I had a Trillium flexipes a few years ago at the Heron Rookery. When I looked at the anther and filament length at home on the computer I was convinced otherwise. But, I must say, in reviewing the two here together I would expect to see more of a difference in the filament and anther length between the two species.

Pete said...

Sorry, I get it now. These photos are both trillium cernuum. Too early in the morning for me to be making comments I guess.

Pete said...

Freel free to delete both the above comments as irrelevant.

Scott Namestnik said...

Pete, thanks to your comments, I've added some photos of Trillium flexipes and a bit more discussion on distinguishing the two. Thanks for the prompt!

Pete said...

Scott, the additional photos of Trillium flexipes are very helpful in distinguishing these two similar species in the field. I have a much better idea of what to look for now. I hope to see more posts like this which compare other similar appearing species.

Scott Namestnik said...

I'd like to do more posts about differences in similar species, Pete... if only there was more time...

A.L. Gibson said...

Nice, Scott! And what are the odds the only time/place I've seen T. cernuum was along the Bog Meadow Nature Trail in Saratoga Co., NY as well! I took my photos on May 29, 2013. Your specimens are fresher than I found mine but it was still wonderful to mark this species off the life list.

Is T. cernuum still extant in Indiana? Color me surprised if it is. It's long, long been extirpated in Ohio and was only collected/recorded once in Lake Co. back in 1879!

Scott Namestnik said...

Thanks Andrew. Really? You saw Trillium cernuum at the same place? That's pretty crazy! I also see it annually at a site in northern Wisconsin, and have some photos from there.

Per IDNR, Trillium cernuum is still extant in Indiana, known from Porter County. I have a good idea of where I could find it, but I've never looked for it. Pete says he had it a few years ago at a site in Porter County. I believe I saw photos and thought it was intermediate, but Pete saw the plant itself and came to the conclusion that it was T. cernuum.

Where was it known from in Lake County? That's where I'm from!

Sorry I'll miss you at the Ohio Botanical Symposium this year. The Missouri Botanical Symposium is the same day and I'll be there.

Scott.

Keith Board said...

Jerry Wilhelm found it in Porter County, Indiana, in 1987 and Barbara Plampin and I tracked down the site years later. It was flowering when we were there. There were only a few plants and it didn't seem like Trillium habitat. It was a Sassafras thicket.

Victor Samuel said...

Hi guys, I've seen how good this blog is. I'm a 200L Plant biology student, University of Ilorin, Nigeria. I'd love to know if there is any chatroom where I can meet new people who are more knowledgeable than me in this field, those who are willing to share their knowledge with others. My G.P is draining, I need to boost it. I'd appreciate replies ASAP...

Scott Namestnik said...

Chat room, not that I'm aware of, but there are plenty of plant identification sites on Facebook.

Vertical garden planter said...

I tend to think that the anther to filament ratio is a better way to distinguish these two similar species than the actual length of the filaments.