Andrachne phyllanthoides (Nutt.) M. Arg.

Buck Brush

Andrachne phyllanthoides plant2

Family - Euphorbiaceae

Habit - Dioecious shrub.

Stems - Ascending to erect, branched, to 1.5 m, woody at base, glabrous or sparsely pubescent, unarmed. Sap clear. Twigs rust-colored, often with some vertical grooves, ribs, or angles.

Andrachne phyllanthoides stemStem and nodes.

Leaves - Alternate, sessile or very short-petiolate, not peltate. Leaf blades 10-18 mm long, broadly elliptic to nearly orbicular, rounded at the base, rounded or shallowly notched at the tip, entire, pinnately veined, glabrous or nearly so, deep green above, lighter below. Stipules scalelike, 1.0-1.5 mm long.

Andrachne phyllanthoides leavesLeaves.

Andrachne phyllanthoides leaves2Leaves abaxial.

Inflorescence - Axillary, the staminate ones of solitary flowers or small, sessile clusters of 2-4 flowers, the pistillate ones of solitary flowers, usually with a small, fringed bract at the base, this to 2 mm long, with ciliate margins. Flower pedicels to 1.5 cm long in pistillate flowers and shorter in staminate flowers, glabrous, thin.

Andrachne phyllanthoides inflorescence

Flowers - Calyces deeply 5(6)-lobed, 1-2 mm long (in pistillate flowers enlarging with maturity), oblong to oblong-obovate, rounded at the tip, glabrous or sparsely hairy, persistent at fruiting. Petals 5(6), 0.5-1.0 mm long (occasionally appearing absent in pistillate flowers), oblong, cream-colored to pale greenish yellow, rounded at the tip, the margins with a minute fringe of hairs. Nectar disc usually more or less divided into 5 lobes opposite the petals, these shallowly and broadly notched at the tip. Staminate flowers with 5 free stamens and an inconspicuous, nonfunctional ovary. Pistillate flowers with the ovary 3-locular, 2 ovules per locule, the 3 styles separate or nearly so, each 2-lobed toward the tip, each lobe broadened into a flattened, knoblike stigma.

Andrachne phyllanthoides flower2Staminate flower.

Andrachne phyllanthoides flowers

Fruits - Capsule 4-5 mm long, 6.0-7.5 mm in diameter, 6-valved, dark purplish brown at maturity, glabrous or nearly so. Seeds up to 6 per fruit, 2.8-3.5 mm long, wedge-shaped, the surface appearing finely pebbled, mottled with darker and lighter brown.

Andrachne phyllanthoides capsuleDeveloping capsule.

Flowering - May - October.

Habitat - Gravel bars, limestone bluffs, knobs, glades.

Origin - Native to U.S.

Other info. - This interesting species can be found in just a handful of southern Ozark counties. It is the only woody member of its family to be found in Missouri and is easy to identify because of its rounded leaves, small flowers, and habitat. Alternate classification schemes have placed this plant into several other genera, and the matter is not completely resolved as yet. Steyermark speculated that this species might be a relict from the time before the last Tertiary uplift, but this view has been disputed. The rest of the woody euphorbs, of which there are many, are all tropical.

Photographs taken in the Ozark Scenic Riverways, Shannon County, MO., 7-6-03 (DETenaglia); also at Drury-Mincy Conservation Area, Taney County, MO, 4-14-2012, and Henning Conservation Area, Taney County, MO, 5-2-2012 (SRTurner).


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