Pilea hyalina Fenzl, Urticaceae

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Present on Pacific Islands?  no

Primarily a threat at high elevations?  no

Risk assessment results:  High risk, score: 8 (Go to the risk assessment)

Habit:  herb

Description:  "Small erect herbs 10-30 cm. tall, bisexual, unbranched or more often with several lateral branches and bush-like form, leafy internodes 4-40 mm. long, 0.4-2.5 mm. thick, glabrous, succulent but drying yellowish and often translucent; stipules rudimentary and less than 1 mm. long, usually obscure. Leaves of the same node of similar size and shape, petioles 4-40 mm. long, 0.2-0.8 mm. thick (dry), glabrous; laminae 0.7-4 (6) cm. long, 0.6-3 (4) cm. broad, ovate to elliptic-ovate or rhombic, acute at the apex, obtuse to abruptly rounded at the base, crenate-serrate or serrate (except near the base) with 3 to 6 teeth per cm., laminae drying membranaceous, upper surface with a few scattered transparent hairs about 0.5 mm. long, the lower surface essentially glabrous, venation palmate with 3 primary veins, midvein with 3 to 7 pairs of obscure secondary veins, short-linear cystoliths usually visible above. Inflorescences in the axils of many nodes and solitary or paired, 3-20 (30) mm. long, short-peduncled but usually much-branched and cymose-paniculate, bisexual but the male flowers soon lost, flowers in congested clusters 1-3 mm. long; male and female flowers about 0.5 mm. long. Fruit 0.3-0.5 mm. long, ovoid to broadly ellipsoid in outline, thick-lenticular with narrowed margins, drying yellowish brown or pale brown"  (Berger, 1977; p. 262).

"Plants annual, the stems erect, mostly simple, succulent and almost transparent, 40 cm. high or less, glabrous; stipules minute, deciduous; leaves of a pair subequal, the slender petioles 4 cm. long or less, the blades thin, rhombic-elliptic or broadly ovate, 1-6 cm. long, 1-3.5 cm. wide, acute, obtuse or broadly cuneate at the base, coarsely serrate, sparsely pilose or villous above, glabrous beneath, with numerous linear cystoliths; flower spikes 2-4 in the axils of almost all the leaves, 2.5 cm. long or less, androgynous, the staminate flowers very few, the pistillate flowers crowded in numerous almost contiguous glomerules; achenes ovate, 0.4 mm. wide"  (Standley and Steyermark, 1952; 24(3)414-415).

Habitat/ecology:  In Costa Rica (native): "plants of seasonally dry or wet evergreen forest formations between (0) 500 and 1800 m.  A succulent-stemmed plant of moist sites and along water courses; completing its life cycle in the wet season"  (Berger, 1977; p. 262).  In Guatemala (native), "moist thickets or forest, frequently a weed in cafetales and other cultivated ground, 250-1,600 meters"  (Standley and Steyermark, 1952; 24(3)414-415).

Propagation:  Seed

Native range:  "Southern Mexico; El Salvador to Panama; tropical South America"  (Standley and Steyermark, 1952; 24(3)414-415).

Presence:

Pacific Rim
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
Chile (continental) Chile	Chile (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2011)
Colombia Colombia	Colombia (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2011)
Costa Rica Costa Rica	Costa Rica (Republic of)	native	Burger, W. C. (1977) (p. 262)
Ecuador (Mainland) Ecuador	Ecuador (Republic of) (continental)	native	U.S. Dept. Agr., Agr. Res. Serv. (2011) Carchi, Chimborazo, Guayas, Los Rios
El Salvador El Salvador	El Salvador (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2011)
Guatemala Guatemala	Guatemala (Republic of)	native	Standley, Paul C./Steyermark, Julian A. (1952) (pp. 24(3)414-415)
Honduras Honduras	Honduras (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2011)
Nicaragua Nicaragua	Nicaragua (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2011)
Panama Panama	Panama (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2011)
Perú Perú	Perú (Republic of)	native	Macbride, J. Francis (1936) (p. 13(2/2)343)

Additional information:
Additional online information about Pilea hyalina is available from the Hawaiian Ecosystems at Risk project (HEAR).

Information about Pilea hyalina as a weed (worldwide references) may be available from the Global Compendium of Weeds (GCW).

Taxonomic information about Pilea hyalina may be available from the Germplasm Resources Information Network (GRIN).

References:

Burger, W. C. 1977. Family 53. Urticaceae. In: W. C. Burger (ed.), Flora Costaricensis. Fieldiana, Bot. 40:218-283. .

Macbride, J. Francis. 1936. Flora of Peru. Field Museum of Natural History, Botanical Series, Vol. XIII. 1936-1971, 6 parts.

Standley, Paul C./Steyermark, Julian A. 1952. Flora of Guatemala. Fieldiana: Botany. Vol. 24, Part III. Chicago Natural History Museum. 432 pp.

U.S. Dept. Agr., Agr. Res. Serv. 2011. National Genetic Resources Program. Germplasm Resources Information Network (GRIN). Online searchable database.