Thursday, November 20, 2008

Unfinished business re: Davallia spp.

In the original Davallia profile, I said that I am not a Davallia taxonomist and do not know what sorts of things differentiate one species from another. Well. I'm still not a Davallia taxonomist, but after going to work and actually looking at some plants, I've discovered that in at least one instance, it's not that hard. Witness:

At work, we have two species of Davallia. One of them is tagged Humata instead, but I think there's a case to be made for calling it Davallia anyway, so I will. 'Cause that's just how I roll. So this one is Davallia "Humata" tyermanii:

And then this other one is Davallia trichomanoides:

Separately, they still look pretty similar, but when you get them side-by-side, the differences start to stand out a bit more:

This side-by-side comparison of fronds is not as dramatic as I'd hoped it might be, but here it is regardless:

The fronds of tyermanii are substantially stiffer and thicker; they're also a darker green in this particular case, but that could be because of the care these particular plants have received, not what species they are. Trichomanoides' fronds are also a little more deeply divided.

The "common names," according to the tags, are: white rabbit's-foot fern (tyermanii) and brown squirrel-foot fern (trichomanoides). The rhizomes don't look especially different to me, and I forgot to get a picture of them together, but the same general rule applies: the trichomanoides rhizomes might have slightly smaller, finer scales, but if there is a difference, it's very subtle. The rhizomes of both have new growth which is light gray to white, which ages to dark brown.

So now you should be able to tell at least these two apart. If I run across other species, we'll revisit the post again.

1 comment:

kittycooks said...

I appreciate your post and pictures. I purchased a white rabbit foot today, tagged as Humata tyermanni, and agree that it is probably a subspecies of Davallia. There is very little authoritative information on the differences, other than country of origin. Thanks for sharing your thoughts! Kittycooks,MN