Wednesday, November 24, 2010
Trillium cuneatum?
Can anyone share thoughts on the identification of this Trillium? I'm labeling photos from 2010 and not sure what it is. Trillium cuneatum seems likely, though it would be a significant range extension where it was found in southern Michigan. It seems possible that it was introduced at the site, a rich forest remnant where it was growing by the hundreds with several other Trillium species. Thanks for any help!
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6 comments:
Presumably Trillium sessile, a state threatened species. T. recurvatum is the only other sessile trillium reported to be native to Michigan. T. luteum is naturalized in several places, but just about any trillium could escape from gardens here, as even the southernmost species are very hardy.
It looks close to T. recurvatum but the recurvatum I've seen in MN have leaves that taper towards the stem and the mottling is 2 colored, dark and light green. Also the petals are much shorter on recurvatum than what's shown in the photo.
How large are these plants? I don't have my refernces with me, but looking at photos online, I don't think the leaf shape (particularly the leaf apex) is quite right for T. cuneatum.
You probably looked at my post a while back that discusses differences between T. sessile and T. cuneatum, but if not, here is an excerpt...
Trillium cuneatum is an extremely variable species, with petal color ranging from maroon to purple to brown to green to yellow, and to all colors in between. Petals are sometimes even bicolored. We saw most of these color variants at Old Stone Fort State Park in Tennessee and at Cloudland Canyon State Park in Georgia. The specific epithet comes from the shape of the petals, which are wedge-shaped at the base and broad above. This trillium was observed in upland woods; it is known to occur in both sandstone- and limestone-based soils. Unlike the species above and below, the flowers of Trillium cuneatum are sessile. This is one big trillie, growing to up to 45 cm tall, with petals sometimes longer than 6 cm. The stigmas of this species are separate to the base, putting it in the subgenus Phyllantherum. Unlike Trillium recurvatum, the sepals are horizontally spreading to erect. Trillium cuneatum may be confused with Trillium sessile, but the anther dehiscense is latrorse in the former and introrse in the latter. Finally, the connectives of the stamens of Trillium cuneatum are barely prolonged beyond the anthers, and the leaves come to an abrupt point.
Not sure that helps much, since you can't see the stamens.
Thanks, all, for your input. When I took the photos I assumed the plants were Trillium sessile and made no attempt to key them. Now it bothers me that the sepals and petals are very long. Unfortunately no photos in the set show stamens, and I didn't measure the petals or sepals. The plants were not excessively tall, in fact they were only about 3 dm. The site was "Trillium Ravine" in Berrien County, Michigan, where several Trillium species seem almost too abundant to be naturally occurring. Even so, it is an excellent and rich forest remnant.
Hi Keith- there appears to be significant variation within the population of T. sessile at Trillium Ravine, and I have observed fairly robust plants there over the years. That said, none of the specimens have ever come close to my experience with T. cuneatum in KY or TN, which I have found to be significantly larger in all aspects. This site has been well-botanized, so I will be very surprised if the trilliums turn out to be the introduced T. cuneatum. As far as the density of trilliums, the site is exceptional for Michigan, but the "toad" trilliums often occur in massive populations, usually on floodplains (and this site is immediately adjacent to the river).
To identify Trilliums it really helps to get a good look at the anthers. The number of them, weather the pollen sacks to all the way up or stop just short, and even if they're to the side or facing inward can help distinguish them.
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