Angiosperms: Dicotyledons

Onagraceae
Evening Primrose Family

• Notes:

  Oenothera pilosella is similar to Calylophus serrulatus except it has longer hairs on the stems. The leaves are oval, tapering to both ends, larger (2 1/2” by 1/2”), without teeth, and long-hairy above and below. The flowers are larger with petals 3/4” long on a 7/8” floral tube, the ovary is 1/2” long, and the sepals are 1/2” long and very hairy. The fruit is shorter (3/8” long) with eight ridges and spreading hairs. Flowering is from early to late June, and fruiting begins in mid-June. O. pilosella is infrequent on sandy, moist prairies.

  O. perennis L., another sundrops, is a rare species and known only from a few locations in eastern Iowa. It is similar in size to C. serrulatus, but the leaves are not toothed. The fruit is smaller (3/8” by 1/8”) and is club-shaped, being larger in diameter beyond the middle, and with four winged ridges. It is found on wet prairies, and it has been collected in the counties designated with P in the map above.

• Bibliography from Biodiversity Heritage Library
• Vascular Plants of Iowa