Hypoxis hirsuta (L.) Coville

Yellow Star Grass


CC = 5
CW = 0
MOC = 73

© SRTurner

Family - Liliaceae

Habit - Perennial forb from a corm, lacking the odor of onion or garlic.

Hypoxis_hirsuta_corm.jpg Corm.

© SRTurner

Stems - Erect, to 25 cm long, unbranched below the inflorescence, sparsely to densely hairy.

Leaves - Basal, usually 2-6, linear, to 30 cm, 3 mm broad, with 5-9 main veins, sparsely to densely hairy.

Hypoxis_hirsuta_leaves.jpg Leaves.

© SRTurner

Inflorescences - Terminal, irregular umbels of 2-6 flowers, sometimes reduced to a single flower, subtended by 1-2 small, linear bracts when young. Pedicels to 2.5 cm long, pubescent.

Hypoxis_hirsuta_inflorescence.jpg Inflorescence.

© DETenaglia

Hypoxis_hirsuta_inflorescence2.jpg Inflorescences.

© SRTurner

Flowers - Perianth 5-13 mm long, spreading, the sepals and petals attached to the top of the ovary, ovate to narrowly oblong or nearly linear, the inner (upper) surface yellow, glabrous, the outer (under) surface yellowish green in bud to usually yellow at flowering, hairy. Stamens 6, attached to the top of the ovary, free from the perianth. Filaments glabrous, 2-3mm long. Anthers orange, 2.1 mm long, sagittate. Style 1, short, slightly thickened near the tip, the stigma 3-lobed, the lobes receptive on the inner surface. Ovary inferior, with 3 locules, each with 3-5 ovules, hairy. Style 1.5mm long, glabrous.

Hypoxis_hirsuta_flowers.jpg Flowers.

© SRTurner

Hypoxis_hirsuta_flowers2.jpg Flowers.

© SRTurner

Hypoxis_hirsuta_tepals.jpg Underside of tepals.

© DETenaglia

Fruits - 3-6 mm long, ovoid, capsulelike but indehiscent, with papery walls.

Hypoxis_hirsuta_fruits.jpg Fruits.

© SRTurner

Hypoxis_hirsuta_seeds.jpg Seeds.

© SRTurner

Flowering - April - May.

Habitat - Mesic to dry upland prairies, glades, exposed bluff tops, dry upland forests, fields.

Origin - Native to the U.S.

Lookalikes - None.

Other info. - This little species is common in Missouri and easily seen even though it is quite small. It occurs throughout most of the state, also ranging across the eastern half of the continental U.S. and into Canada. It is easily recognized by its bright yellow flowers, grasslike leaves, and diminutive stature. The small yellow flowers open in the morning and typically wilt in hot sun. The amount of pubescence can be variable, as well as the size of the foliage and flowers. The seeds are covered with tiny bumps or spines, and anthers diverge in the lower half, giving the stamens an "arrowhead-like" appearance.

When not in flower, the plants resemble a grass, but the term "yellow star grass" is a misnomer because the plant is not a grass but rather a lily (broadly speaking). The family affinity is somewhat unsettled at present, with some botanists placing it in the Image

Photographs taken at the Piney Creek Wilderness, Mark Twain National Forest, Barry County, MO., 4-9-01, at Earthquake Hollow, Callaway County, MO., 4-22-04, and at Bibb County Glades, Bibb County, AL., 5-1-05 (DETenaglia); also at Pickle Springs Natural Area, Ste. Genevieve County, MO, 5-3-2008, Valley View Glade Natural Area, Jefferson County, MO, 4-10-2010 and 5-6-2018, and Shaw Nature Reserve, Franklin County, MO, 5-26-2022 (SRTurner).