the flower, flopped over, which they seem to do a lot

Krigia species
Asteraceae

Say you’ve narrowed an ID down to the genus, but just can’t figure out which species you have. To be absolutely sure, you probably need to consult a flora, but if you’re like me, you’ll be spending most of your time looking up the jargon, only to realize you don’t have the info you need anyway.

Take this plant, for example. For three years now I’ve been keeping an eye on a small patch near the C&O Canal towpath. I’m absolutely positive that it’s a Krigia species. But which one, Krigia virginica or Krigia dandelion?

After going through the process described in the past three posts, I still couldn’t figure it out. So I posted a few pictures and asked the question on the MNPS discussion page on facebook. One member helpfully pointed me to Weakley’s Flora of the Southern and Mid-Atlantic States.  In the Asteraceae key (page 1,145) was this:

“Pappus of 5 scales and 5 bristles; plant a winter annual; stem leafless or leafy at the base only…..K. virginica

…Pappus of 15-40 scales and 15-40 bristles; plant a perennial; stem leafless, leafy at the base only, or with many leaves extending up the stem. [go to 4]

…4 Stems leafless, the peduncles terminal; perennial from ovoid tubers, with long slender stolons which form new plants or tubers; pappus bristles (5.0-) 5.3-7.7 (-10.0) mm long…..K. dandelion”

OK, then. First, what is a “pappus”? It’s the tuft of hairs on seeds of plants in the aster family.

And right away I’m stumped again. I’ve never seen the seeds. It’s not like I visit this patch every day! If this ridiculous rainy weather ever clears up I’ll try going out there again, and hopefully the plants will have developed seeds, and hopefully those seeds won’t have blown away yet. [update: the day after writing this, I went back; 3 flowers, one fading, but none gone to seed yet]

the bud

But there are other clues in this flora. Are the plants perennials or winter annuals? I don’t know. I’m going to have to observe them closely over the season to determine that. I have reason to believe they’re perennial, but I’m not sure. If they are, they’re K. dandelion.

Next clue: the description of the stem. Not useful, since the stems of both species can be leafless. What I’ve seen in all the patch is a basal rosette of leaves and a single leafless flowering stem per plant. I’ve never seen leaves on the stem.

the flowering stem

Next clue: “…with long slender stolons which form new plants…” Well, it’s a patch of plants. Is it a patch from annuals that re-seed every year? From my gardening experience, I doubt it. These seeds will be wind-dispersed; if the plants were reseeding annuals, I’d see them scattered over a large area. What I’m seeing is a very tight cluster of plants growing close together, which suggests (but does not prove) stolons.

Next clue: “ovoid tubers”. Here’s a bit of info that I just can’t get. First, these plants are on National Parks land, where digging is forbidden (and rightly so). And second, K. dandelion is an endangered species in Maryland, ranked S1 (“typically 5 or fewer estimated occurrences or very few remaining individuals or acres in the State”). Even if it were legal, there’s no way I would dig up an S1/endangered plant! But seeing the roots would certainly solve the mystery.

the basal rosette

So still no answer. But, there’s nothing like the word of an expert. Fellow MNPS member Joe Metzger, who’s been doing this for forty some years, wrote:

“Notice the fact that there is a single large flower. Dwarf Dandelion (Krigia virginica) would have a cluster of flowering stems, each with a flower. This is an adaptation common in many annuals to insure seed is produced. Yours has only one flower and no indication of any others. The basal leaves in your photo are strap shaped and either entire or shortly dentate which is another good indication that is Potato Dandelion (Krigia dandelion). On Dwarf Dandelion they would rarely ever be entire and they are deeply dentate or serrate and not usually strap shaped, usually tapering at each end.”

So there it is. Not definitive proof, but the available information strongly suggests that this is Krigia dandelion (potato dwarf dandelion), a Maryland endangered species.

Whoo-hoo!