Thursday, May 22, 2014

Sample Size is Important

What is this flower?
            I spent well over two hours last night trying to get an ID on a new flower blooming in the vacant-lot prairie. It wasn't in my wildflower books, at least not that I could recognize, and I was really thrown by it's combination of features. It had a disc like a sunflower, but what should have been simple rays were notched twice. It looked like a cross between a sunflower and a gaillardia.
            I was stumped- sunflower's disc, gaillardia's rays. Blue-grey-green foliage with scattered spiney serrations along the leaf edges. What to do? Well, I sent up a distress flare to my botanically inclined contacts. What's weedy, has notched rays, a sunflower-like disc, and grows in Texas? I needed to know.  After consulting with my naturalist friends, we decided it was a weird-looking Texas blue weed (Helianthus ciliaris). Generally, when you can't quite convince yourself an ID is right, that's because it isn't.
A more typical Helianthus ciliaris, taken with my iPhone.
            Not in this case, however.  I visited the plant again the next morning (such was my desire to GET IT IDENTIFIED), and another bud had opened. No notches in the rays. Now I could rest easy, having found a second, fairly typical, specimen of blueweed. Individual idiosyncrasy is the risk you run when you only have a few specimens from which to make a judgment. I actually liked the extra decorative flourish from my unusual variant's notched petals, but they sure did throw me. When I dug a little deeper to find out more about this new plant, a descriptor that stuck out to me was "highly variable".  That phrase tipped me over into certainty of my ID.
            Despite its weediness, blueweed is actually native to the southwest.  In Texas, blueweed is more typical of the panhandle and trans-pecos region than it is of the metroplex. Livestock don't eat it, it reproduces by rhizome, and it prefers poor soils and disturbed areas. Another term associated with this new flower: noxious weed.  
            Blueweed is classified as a "noxious weed" in the states of Washington and Oregon. This plant can be aggressive. It's highly drought tolerant, and, like cattails and phragmites, it grows from rhizomes. This means that mechanical chopping of the roots can multiply your problem. Like a starfish, each fragment regenerates into a new plant. Biological control isn't an option either- blueweed is highly resistant to natural pests. Sunflower beetles leave them alone.
            It is intriguing to see this sunflower functioning as a small part of my urban prairie, while in other places it can be a real problem. Washington state's King County noxious weed page suggested that perhaps it is our native grasses down here that help reign in this weed. Competition from our diverse grassland may keep blueweed from becoming an aggressive pest in its home turf, but there is no such checking force in the Pacific Northwest. I suppose this plant could serve as a reminder: what seems innocuous at home isn't always universally so. We should be careful with what we plant.

In other news, I added three new species to my vacant-lot prairie plant list. These include the aforementioned Helianthus ciliaris, and also Cooperia drummondii, and Asclepias viridis.

Another picture of ratany- to me it looks like an orchid when the flowers are open
I've included more pictures and the updated plant list after the jump. 

Pink ladies, Oenothera speciosa

texas vervain, Verbina halei

Cooperia drummondii

Asclepias viridis?

Common Name Latin Name Date Observed
antelope horn Asclepias asperula 17-May
green antelope horn Asclepias viridis
evening rain lily Cooperia drummondii 17-May
hill country rain lily* Cooperia pedunculata 17-May
engelmann daisy Engelmannia peristenia 17-May
indian blanket Gaillardia pulchella 17-May
scarlet gaura Gaura coccinea 17-May
prairie verbena Glandularia bipinnatifida 17-May
texas blue weed Helianthus ciliaris 22-May
ratany Krameria lanceolata 17-May
lantana Lantana urticoides 17-May
texas bluebonnet Lupinus texensis 17-May
sensitive briar Mimosa nuttallii 17-May
yellow-puff Neptunia lutea 17-May
pink ladies Oenothera speciosa 17-May
texas frog fruit Phyla nodiflora 17-May
prairie parsley Polytaenia nuttallii 17-May
prairie coneflower Ratibida columnifera 17-May
two-leaf senna Senna roemeriana 17-May
carolina horse nettle Solanum carolinense 17-May
diamond flowers Stenaria nigricans var. nigricans 17-May
green thread Thelesperma filifolium 17-May
western spiderwort* Tradescantia occidentalis 17-May
texas vervian Verbena halei 17-May

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