Lygodsemia juncea (Pursh) Hook.
Family - Asteraceae
Stems - To 50cm tall, glabrous, often glaucous, erect, branching (branches erect and parallel to main axis), multiple from a thick woody rhizomatous rootstock, with vertical striations. Plant with milky sap.
Leaves - Alternate. Cauline leaves reduced and scalelike, +/-7mm long, scabrous, subulate. Basal leaves few (if any), linear-lanceolate, to +3cm long.
Inflorescence - Single flower head terminating the stem. Flowerheads typically with 5 flowers per head.
Involucre - To 1.4cm long(tall), with 2-3 series of outer phyllaries and 1 long inner series of phyllaries. Phyllaries glabrous, with scarious margins, typically with a brownish tip. Outer phyllaries acute, 2-3mm long. Inner phyllaries to 1.3cm long, 2mm broad, linear.
Ray flowers - Fertile, perfect. Ligules pinkish-purple, to +1cm long, typically 5-toothed(notched) at apex, glabrous. Corolla tube white, 1cm long, glabrous. Style purplish, bifurcate. Anthers connate around style, purplish, to 4mm long. Achenes glabrous, angled, greenish, 1.7mm long in flower, 1cm long in fruit. Pappus of capillary bristles.
Disk flowers - Absent.
Flowering - June - August.
Habitat - Exposed dry loess hills.
Origin - Native to U.S.
Other info. - Although I have not seen it myself, this species is frequently seen with globose galls
caused by a small wasp. Galls are not actually caused by the insect larvae
themselves, rather, galls are formed by a soil-borne bacteria carried on
the insect larvae. The bacteria is known as Agrobacterium tumefaciens
and is widely used in genetic recombination techniques with plants. There
is a wealth of information out there if you want to read more about A. tumefaciens.
Photographs taken at the Jamerson C. McCormack Conservation Area, Holy County, MO., 6-30-00.