Matricaria matricarioides (Less.) Porter - Pineapple Weed

Matricaria matricarioides plant

Family - Asteraceae

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

Matricaria matricarioides 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 matricarioides 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 matricarioides 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 matricarioides 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 none the less. The green subglobose flower heads are eye-catching. The plant is often not seen because of its small size. I must admit, I nearly stepped on it the first time I saw it.

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