Paspalum pubiflorum Rupr. ex E. Fourn.

Hairy-Seed Bead Grass


CC = 3
CW = 0
MOC = 62

© SRTurner

Family - Poaceae/Paniceae

Habit - Perennial grass, without rhizomes, forming tufts or clumps, with C4 photosynthesis.

Stem - Ascending from usually spreading bases, to 1 m, sometimes rooting at lower nodes, glabrous or nearly so.

Paspalum_pubiflorum_stem.jpg Lower stem and leaves.

© SRTurner

Leaves - Leaf sheaths glabrous or the lowermost ones sparsely hairy, the ligule membranous, 0.8-2.5 mm long. Leaf blades 5-30 cm long, 4-15 mm wide, usually sparsely hairy toward the base.

Paspalum_pubiflorum_leaves1.jpg Leaf blades, adaxial.

© SRTurner

Paspalum_pubiflorum_leaf2.jpg Leaf abaxial.

© SRTurner

Paspalum_pubiflorum_sheath.jpg Sheath.

© SRTurner

Paspalum_pubiflorum_ligule.jpg Ligule.

© SRTurner

Inflorescences - Panicles with 3-10 spikelike branches mostly more than 2 cm apart along the main axis. Spikelike branches 4-11 cm long, erect to spreading, one-sided with a persistent axis, with a spikelet at the tip, narrower than the band of spikelets, the spikelets dense and mostly strongly overlapping along the axis, mostly in 2 rows of paired spikelets, appearing as in 4 rows.

Paspalum_pubiflorum_inflorescence1.jpg Inflorescence.

© SRTurner

Paspalum_pubiflorum_inflorescence2.jpg Spikelike inflorescence branches.

© SRTurner

Paspalum_pubiflorum_inflorescence3.jpg Axis of spikelike branch.

© SRTurner

Paspalum_pubiflorum_inflorescence4.jpg Rows of spikelets.

© SRTurner

Spikelets - Elliptic-ovate in outline, 2.8-3.2 mm long, rounded or bluntly pointed at the tip. Lower glume absent. Upper glume 2.6-3.2 mm long, elliptic-ovate, rounded to bluntly pointed at the tip, 3-7-nerved, glabrous or nearly so. Sterile floret with the lemma 2.6-3.2 mm long, elliptic-ovate, rounded to bluntly pointed at the tip, 5-7-nerved, glabrous. Fertile floret with the lemma 2.4-3.0 mm long, elliptic. Anthers 0.8-1.2 mm long, black.

Paspalum_pubiflorum_spikelets.jpg Spikelets.

© SRTurner

Paspalum_pubiflorum_functional.jpg Anthers and styles.

© SRTurner

Fruits - Caryopses broadly oblong-elliptic in outline.

Flowering - June - September.

Habitat - Upland prairies, bottomland forests, pond margins, streambanks, pastures, fields, lawns, ditches, roadsides, railroads, moist, open, disturbed areas.

Origin - Native to the U.S.

Lookalikes - Other species of Paspalum, especially P. floridanum, P. setaceum, P. laeve, and others.

Other info. - The generic term "bead grass" seems appropriate to grasses in this genus, as they generally present their spikelets in neat rows resembling tiny beads crowded on a string. Identification to species is a little more difficult. Important features of this species include several spikelike branches on the inflorescence, branch axes which are narrower than the rows of spikelets (such that the spikelets are easily visible from above), and rows of spikelets which appear 4-ranked. Steyermark also noted the tendency of the lower stems to recline along the ground, sometimes rooting. All of these characters are somewhat variable and can confound a confident determination. Spikelet length (2.8-3.2 mm) is also a good character for identification but requires either a microscope and microruler or else lots of experience to evaluate.

Missouri plants are referable to var. glabrum An alternate form, var. pubiflorum, has hairy spikelets, and is found to our south. The species occurs throughout the lower Midwest, extending to the Gulf Coast. In Missouri it occurs in the southern 2/3 of the state.

Photographs taken at Don Robinson State Park, Jefferson County, MO, 9-2-2021, and near Labadie, Franklin County, MO, 9-3-2021 (SRTurner).