Matricaria discoidea DC.

Pineapple Weed

Matricaria discoidea plant

Family - Asteraceae

Stems - Multiple from base, from taproot, ascending to erect, glabrous or with a few sparse hairs, to +15cm tall, herbaceous.

Matricaria discoidea stemStem.

Leaves - Alternate, sessile to very short petiolate below, to +1.5cm long, +7mm broad, deeply pinnatifid to bipinnatifid. Ultimate divisions linear, lanate (sparse), green.

Matricaria discoidea leaves

Inflorescence - Loose cymose arrangement of terminal flower heads. Heads globose to ovoid, to 8mm in diameter, with +100 flowers (florets).

Involucre - To 5mm tall. Phyllaries in two series, scarious-margined.

Matricaria discoidea involucreInvolucre.

Ray flowers - Absent.

Disk flowers - Green, 4-lobed, 1.1mm long, glabrous. Achenes to 1.1mm long, tan in flower, terete, ribbed. Pappus a minute crown or absent. Receptacle conic.

Matricaria discoidea flowers

Flowering - May - October.

Habitat - Rocky open ground, pastures, waste ground, disturbed sites, roadsides, railroads.

Origin - Native to Western North America and Eurasia, introduced in many parts of the U.S.

Other info. - This is a tiny plant but interesting nonetheless. The green subglobose flower heads are eye-catching. The plant is often found in heavily traveled disturbed areas and even sidewalk cracks. The crushed foliage emits a distinctive aroma similar to pineapple; thus the common name.

Photographs taken at Taberville Prairie, MO., 6-7-03.