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The
richly-colored
flowers and the abundance of Dieteria bigelovii and Dieteria
canescens make them very conspicuous in late summer and
fall. In most years both Dieteria species put on magnificent flower displays in foothill fields and along roadsides.
They are long lasting, often blooming into late October and even November. The two species hybridize making species identification quite
difficult. Making identification even more difficult are the many
varieties of M. canescens.
William Weber states that there are two keys to distinguishing between the two species: 1) Dieteria bigelovii's peduncles (the common stalk of the flower cluster) are very sticky; Dieteria canescens' are not. In the photograph below of Dieteria bigelovii, you can see the gleaming dots of the sticky, glandular hairs covering the phyllaries, flower stem, and small leaf-like structures. You can also see small buff-colored sand particles stuck to these hairs. About half-way up the stem on the right side, a black ant is feeding on the sticky sweetness.
2) Both Dieteria bigelovii and Dieteria canescens have phyllaries in over-lapping rows with curved tips, but Dieteria bigelovii's phyllaries (left photograph below) are green at the tip and for at least half the length of the phyllary. Dieteria canescens' phyllaries are green only at the tip and the lower three-fourths of the phyllary is tan/white (often with a very narrow green stripe in the center). A hand lens will help you observe the phyllary characteristics in the field. I find that many plants mix the above characteristics: some have sticky peduncles (Dieteria bigelovii) but phyllaries green only at the tip (Dieteria canescens).
Phyllaries of both pants are sticky and you will often find various wind-blown particles stuck to the phyllaries. See especially the left photograph for the sand particles stuck to the flower stem and phyllaries. The slightly toothed leaves of both plants are narrow, but those of M. bigelovii are usually narrower. Dieteria bigelovii is usually a bit taller (but both plants can exceed three feet), less branched, and has fewer flowers. Dieteria bigelovii flowers tend to be deep violet to blue-white; Dieteria canescens are lavender-pink. M. canescens can be a crumply, raggedy plant with flower petals curling like wood shavings from a carpenter’s plane. Dieteria canescens stems are rough, not sticky, and sometimes brown-red and stiff. Stanley Welsh, Utah flora expert, indicates that only Dieteria canescens exists in Utah. As the map below indicates, that would mean that almost every Colorado county on the border with Utah has Dieteria bigelovii but not one Utah county bordering Colorado has the plant. That is highly unlikely -- but does not necessarily mean that Welsh is incorrect. I lean much more toward saying that the reason Welsh does not show Dieteria bigelovii in Utah is that he does not believe the plant can be distinguished from Dieteria canescens. My own experience shows that the two plants have overlapping characteristics and should be combined under one name, either Dieteria canescens or Dieteria bigelovii. "Machaer" is Greek for "sword" and "anthera" is Greek for "anthers" from "anthos", "flower". "Machaeranthera" thus refers to the sword shape of the anther tips. In his excellent etymological web site, CalFlora, Michael Charters indicates the following for the meaning of Dieteria: "according to David Hollombe, Nuttall indicated that he intended the meaning of this name to relate to its biennial habit, and the only possible derivations I can come up with are di-, "two or twice," and etesios, 'yearly' ". |
Species present in state and native
Species present in state and exotic
Species not present in state
Species present and not rare
Species present and rare
Species extirpated (historic)
Species extinct
Species noxious
Species exotic and present
Eradicated
Questionable presence
