Parietaria

Herbs, annual or perennial, sparsely to densely pubescent with hooked and straight, nonstinging hairs on all parts of plant, stinging hairs absent. Stems often branched from base, erect, ascending, or decumbent. Leaves alternate; stipules absent. Leaf blades deltate, orbiculate to narrowly elliptic, or lanceolate, margins entire; cystoliths rounded. Inflorescences axillary. Flowers bisexual, staminate, or pistillate, proximal flowers usually bisexual and staminate, distal flowers pistillate; involucral bracts linear to lanceolate, without hooked hairs; tepals 4, distinct, ascending, lacking hooked hairs; stamens 4; style persistent or not; stigma tufted, deciduous. Achenes stipitate, ovoid, acute or mucronate (style base sometimes persisting as apical or subapical mucro), loosely enclosed by tepals. x=7, 8, 10, 13.

Distribution

Primarily in temperate and subtropical regions.

Discussion

Species 20-30 (5 in the flora).

Mature achenes are necessary for certain determination.

Parietaria nummularifolia (Schwartz) Weddell was collected once in 1992 in Palm Beach County, Florida, in mesic woods bordering a creek (R.P. Wunderlin, pers. comm.). This species is occasionally cultivated, and the Florida collection probably represents an escape.

Selected References

None.

Lower Taxa

Parietaria floridana, Parietaria hespera, Parietaria judaica, Parietaria pensylvanica, Parietaria praetermissa

Key

1	Herbs perennial; achenes dark brown, apex acute, mucro absent or minute.	Parietaria judaica
1	Herbs annual or short-lived perennial; achenes light brown, apex obtuse, mucro distinct, apical or subapical.	> 2
2	Leaf blades orbiculate to deltate, apex smoothly attenuate or occasionally slightly acuminate; achenes less than 0.9mm, stipes short-cylindric, abruptly flared basally.	Parietaria floridana
2	Leaf blades ovate to narrowly elliptic or lanceolate, or if deltate or orbiculate, then apex acuminate; achenes 0.9mm or more, stipes basally dilated cylinders.	> 3
3	Mucro subapical; stipe not centered.	Parietaria praetermissa
3	Mucro apical; stipe centered.	> 4
4	Leaf blades narrowly to very broadly ovate, oblong, orbiculate, or reniform, base rounded; proximal pair of lateral veins arising at junction of blade and petiole; involucral bracts usually more than 2 times length of achene.	Parietaria hespera
4	Leaf blades narrowly to broadly elliptic, lanceolate, oblong, or ovate, base narrowly cuneate; proximal pair of lateral veins arising distal to junction of blade and petiole; involucral bracts usually less than 2 times length of achene.	Parietaria pensylvanica