yourpals favoriter

First image female flower. Second image male. 5th & 6th image female Plants dioecious and abundant at this location. Nearly 60% of hosts (Dalea frutescens) infected.

Re: flower morphology:
The species is dioecious so all flowers are unisexual. The flowers lack petals. The perianth is a spiral of sepals. Male and female flowers arrange their sex organs on a unisexual column (like unisexual orchids in the genus Catasetum). In both flowers the central column terminates in a fleshy disc I presume would be called a compitum. In female flowers the receptive, stigmatic papillae ar arranged under the compitum on the surface of the style. In male flowers the column is a pistilode also with a fleshy compitum. Sessile anthers re fused to the pistilode style. That's the best I can do at short notice. Have you seen the attached? I think the illustration is quite clear. How many stamens can you count attached to the pistilode neck?

Here's what we use to identify var. davisii:

-habitat is along rivers, usually older non-active sandy cobble bars that have re-vegetated to varying degrees, but also occasionally on active river shorelines

-leaflets are irregularly whorled (not all whorled, like O. splendens, and not all paired, like other species of Oxytropis)

-there are minute club-shaped structures scattered along the edge of the stipule among the straight hairs (tear leaf base carefully off a fresh plant and examine with hand lens in good light from the inside - it's really hard to find these structures without removing the leaf base from the plant)

-the flower colour varies between dark pink and light purple, but is not as bright pink as O. splendens

-the inflorescence in flower is relatively shorter than the very long infloresence of O. splendens in flower

-the leaves are grayish green to green in aspect (compared to O. splendens leaves that have abundant silky pubescence and so look gray and fuzzy)

That said, we do find forms intermediate between O. campestris var. davisii and O. splendens as mentioned in Welsh's 1991 paper on p. 394, and that complicates things.

https://www.biodiversitylibrary.org/part/248313