Xerophyte

Seeds

Elm shaped, 2 mm long, shining, black with large oblong hilum nearly as long as the body.

Roots

Long tuberose, inversely conical 2-3 cm wide.

Flowers

Arising from the crown from a very woolly bud, often cleistogamous, 2 to 2.5 cm, up to 3 cm diameter, pale yellow, with dense, whitish to rose-colored pubescence outside. Inner perianth-segments lanceolate, acute, yellow; filaments and style white; stigma-lobes yellowish. But don't be disappointed when the easily produced buds fail to open. Fraileas are cleistogamous meaning that their flowers produce seed without even opening. Without the need for pollination, hence the buds rarely reach full bloom and remain closed. They will open only in great heat in the hottest, brightest, afternoon sun, if at all.

Blooming Season

Hottest part of summer.

Spines

6-10 quite fine, short, bristly, setaceous, glassy, white radial spines, 1-4 mm long, adpressed and rarely also one or two small central spines. They are straight or slightly curved. Some forms have longer white spines that are basally orange yellow in colour while other have yellow spines and wool.

Ribs

13-21 ribs, quite flat divided by transverse depression into tiny tubercles (more noticeable when the body is dehydrated).

Stem

Typical F. pygmaea has a flattened, light green to dull green body, depressed at the crown, , with a turbinate base, 1 to 3 cm in diameter. Some forms have distinctive dark crescent-shaped marks below the areoles.

Fruits

Dry indehiscent that detach easily, pear-shaped, 1,5 cm tall, 1 cm in diameter, with short matted hairs and with a pointed head of bristles. The fruit wall is thick, membranous, fragile and it opens by a basal pore to release the seeds that are promptly harvested by ants.

Areoles

At first with witish or slight yellow wool.