Trifolium pratense L.

Trifolium pratense plant

Family - Fabaceae

Stems - Typically sprawling to erect or ascending, to +60cm tall, herbaceous, glabrous to villous or hirsute, branching, multiple from base, purplish below.

Trifolium pratense stem

Leaves - Alternate, trifoliolate, petiolate, stipulate. Stipules to +2cm long, with long bristle tip (to 6mm), striate-nerved for bottom 2/3 and reticulate-nerved for top 1/3, sparsely hirsute. Petiole sparse hirsute, +/-10cm long. Leaflets lanceolate to broadly ovate, entire to serrulate, rounded to emarginate at apex, 1-7cm long, 1-4cm broad, typically sericeous on both surfaces but sometimes glabrous above, with light-colored "V" in center. Petiolules to +/-1.2mm long or absent.

Trifolium pratense plant

Inflorescence - Terminal globose capitate cluster of 20-100 flowers. Flowers sessile. Peduncles to 2cm long, hirsute, subtended by reduced leaves (or flower heads sessile).

Trifolium pratense inflorescence

Flowers - Corolla papilionaceous, pink to rose (rarely white), glabrous. Standard to 1cm long, 3-4mm broad. Stamens diadelphous. Style to 7mm long, glabrous. Calyx weakly bilabiate to 5-lobed, tube to 3.5mm long, -2mm in diameter, whitish, sparse hirsute. Lobes green, with one longer and larger than the other four. Larger lobe (the middle lobe of the bottom lip) to 5mm long. Shorter lobes to 3mm long. All lobes linear, ciliate-margined, pubescent, floccose between lobes. Legumes to 2mm long, 1-2 seeded, brownish-yellow.

Trifolium pratense flowersFlowers close-up.

Flowering - April - September.

Habitat - Waste ground, disturbed sites, fields, roadsides, railroads.

Origin - Native to Europe.

Other info. - If you live in Missouri you have seen this plant. This introduced species is one the most common plants in this state. It thrives in waste areas and forms large clumps. The large pink flower heads and distinctly marked leaflets are unmistakable.
Steyermark divides the species up into different varieties and forms depending on leaflet size, plant height, and flower color, but I won't go into those here.

Photographs taken in Eminence, MO., 6-6-03, and in Springfield, MO., 7-5-03.


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