Pilea pumila (clearweed)

Pilea pumila (L.) A. Gray

Clearweed

Kingdom	Plantae	Plants, but not fungi, lichens, or algae
Subkingdom	Tracheobionta	Vascular plants—plants with a “circulatory system” for delivering water and nutrients
Division	Magnoliophyta	Flowering plants, also known as angiosperms
Class	Magnoliopsida	Dicotyledons—plants with two initial seed leaves
Subclass	Rosidae	Roses, legumes, proteas, dogwoods, hydrangeas, mistletoes, euphorbias, grapes, many more
Order	Urticales	Includes cannabis, nettles, mulberries, elms, others
Family	Urticaceae	Nettle family
Genus	Pilea	Mostly succulent herbs; from Greek pilos, “cap” (from the shape of some flower parts)
Species	pumila	Means “dwarf”

About plant names...

Clearweed is a North American native, a member of the nettle family.

Plants: Clearweed is 6-24" (15-60 cm) high, with smooth, round stems that are somewhat translucent. These plants resemble other nettles, including stinging nettle, but they lack the hairs that cause the sting.

Leaves: In opposite pairs, each 1-5" (2.5-12 cm) long by ½-2½" (1.3-6.3 cm) wide. Leaves are oval-shaped and coarse-toothed, with three prominent veins and textured leaves. The leaves are bright green, usually shiny, and become yellow in the fall.

Flowers: Both male and female flowers are found on each plant. Individual flowers are ⅛" (3.2 mm) long, greenish-white or greenish-yellow. They drop in narrow bunches from the axils of the upper leaves.

Fruits: Tiny green seeds (achenes) sometimes have black stripes.

8/22/2012 · Squannacook River Wildlife Area, Townsend, MA
≈ 7 × 4½" (17 × 11 cm) ID is uncertain

8/22/2012 · Squannacook River Wildlife Area, Townsend, MA
≈ 9 × 6" (22 × 14 cm) ID is uncertain

8/22/2012 · Squannacook River Wildlife Area, Townsend, MA
≈ 6 × 4" (15 × 10 cm) ID is uncertain

See this article by Steve Brill on distinguishing among nettles and related plants. Here are some similar species:

	*Laportea canadensis*	*Boehmeria cylindrica*	*Acalypha rhomboidea*
Common Name	wood nettle	false nettle	three-seeded mercury
Plant	24-48" (60-121 cm) high. Stems have *stiff white hairs that sting* if you rub against them.	4-63" (10-160 cm) high, and favor shady wooded areas. Stems are smooth, without the irritating hairs of stinging nettle.	6-24" (15-60 cm) tall, with a stem that is *hairless or covered with fine white hairs. Bracts beneath flowers, stems, and leaf undersides turn copper-colored*.
Flowers	Male flower clusters are white or greenish white, in loose branching clusters. Each flower is less than ⅛" (3.2 mm) across, with 5 petals. They appear from July to September.	Flowers *occur on straight spikes that emerge from the stem,* in clusters of small, inconspicuous green flowers. Each spike is often tipped by a couple of small leaves. Flowers appear from July to August.	Flowers are greenish-tan, and tiny—less than ⅛" (3.2 mm) across. They flower from July to October.
Leaves	Alternate, up to 4" (10 cm) × 6" (15 cm), egg-shaped, with coarse serrations.	Usually opposite or nearly so. They are roughly egg-shaped, with sharp tips and teeth. (More precisely, they are elliptic, lanceolate to broadly ovate.) The leaves are 1¾-7" (5-18 cm) × ¾-4" (2-10 cm).	Leaves are alternate, lance-like or oval with sharp tips, 3½" (8.9 cm) × 1" (2.5 cm), with blunt serrations.
Fruit	Oblique dry seeds.	Spiky little balls.	A 3-lobed roughly spherical fruit containing 3 seeds.
Range/ Zones
Habitats	Moist woods, streambanks, in rich soils	Moist, deciduous woods; wet meadows; swamps, bogs, and mashes	Open woods, moist soils, gravel bars, waste ground, roadsides, railroads.
Type	Wild	Wild	Wild

	*Urtica dioica ssp. gracilis*	You are here Pilea pumila
Common Name	stinging nettle	clearweed
Plant	24-39" (60-100 cm) high, rarely up to twice that. The entire plant is covered in stinging hairs.	6-24" (15-60 cm) high, with smooth, round, translucent stems. They *do not have stinging hairs*.
Flowers	Plants are monoecious—male staminate flowers appear on the same plants as female pistillate flowers. Male flowers are grayish yellow, with four tepals. Female flowers have four tepals too, but in different-sized pairs. They are gray-green and hairy. The flower clusters resemble catkins.	Both male and female flowers are on each plant. Fowers are ⅛" (3.2 mm) long, greenish-white or greenish-yellow, hanging in narrow bunches from the axils of the upper leaves.
Leaves	Opposite, oblong, cordate, and serrate (with sawtooth edges). They are 1-6" (3-15 cm) long.	Leaves occur in opposite pairs, each 1-5" (2.5-12 cm) long by ½-2½" (1.3-6.3 cm) wide. Leaves are oval-shaped and coarse-toothed, with three prominent veins and textured leaves. The leaves are bright green, usually shiny, and become yellow in the fall.
Fruit	Each inner pair of tepals encloses a single deltoid to ovoid seed.	Tiny green seeds (achenes) sometimes have black stripes.
Range/ Zones
Habitats	River deltas, floodplains, margins of deciduous woodlands, fencerows, and waste places	Wet upland or floodplain forests, crevices in rocky canyons, and shady wetlands, streambanks.
Type	Wild	Wild

Online References:

Pilea pumila on Missouriplants.com

Pilea pumila at Illinois Wildflowers

Pilea pumila at the University of Wisconsin's Robert W. Freckmann Herbarium

Pilea pumila on Southeastern Flora, the Southeastern U.S. Plant Identification Resource

Pilea pumila on Ontario Wildflowers

Pilea pumila at the Lady Bird Johnson Wildflower Center

References:

Newcomb, Lawrence, Morrison, Gordon (Illus.), Newcomb’s Wildflower Guide, Little, Brown and Company, 1977, p. 438

8/8/2010 · Jeff Smith Trail, Beaver Brook Association Conservation Lands, Rte. 130, Hollis, NH
≈ 4 × 6" (10 × 15 cm) ID is uncertain

10/17/2016 · Ice Glen, Stockbridge, MA
≈ 7 × 10" (16 × 24 cm)

8/22/2012 · Squannacook River Wildlife Area, Townsend, MA
≈ 9 × 6" (22 × 14 cm) ID is uncertain

8/18/2012 · Nashua River Rail Trail, Groton Center, Groton, MA
≈ 5 × 8" (13 × 19 cm)

9/27/2010 · Nashua River Rail Trail, Groton Center, Groton, MA
≈ 6 × 9" (15 × 23 cm) ID is uncertain

8/16/2013 · Nashua River Rail Trail, Groton Center, Groton, MA
≈ 7 × 10" (16 × 25 cm)

8/18/2012 · Nashua River Rail Trail, Groton Center, Groton, MA
≈ 5 × 8" (13 × 19 cm)

Pilea pumila description by Thomas H. Kent, last updated 16 Sep 2020.

9/27/2010 · Nashua River Rail Trail, Groton Center, Groton, MA
≈ 8 × 12" (20 × 31 cm) ID is uncertain

10/17/2016 · Ice Glen, Stockbridge, MA
≈ 7 × 4½" (18 × 12 cm)

8/8/2010 · Jeff Smith Trail, Beaver Brook Association Conservation Lands, Rte. 130, Hollis, NH
≈ 7 × 11" (18 × 28 cm) ID is uncertain

8/22/2012 · Squannacook River Wildlife Area, Townsend, MA
≈ 7 × 4½" (17 × 11 cm) ID is uncertain

9/29/2010 · Nashua River Rail Trail, Ayer, MA
≈ 12 × 8" (31 × 20 cm) ID is uncertain

8/8/2010 · Jeff Smith Trail, Beaver Brook Association Conservation Lands, Rte. 130, Hollis, NH
≈ 7 × 10" (16 × 25 cm) ID is uncertain

9/27/2010 · Nashua River Rail Trail, Groton Center, Groton, MA
≈ 6 × 9" (15 × 23 cm) ID is uncertain

Range:

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