Urtica pumila sensu Euphras. ex Griseb., Fl. Brit. W.I.

K. K., Jeomol & Sunojkumar, P., 2020, Pilea hyalina (Urticaceae), a new record for Asia from Peninsular India, Rheedea 30 (2), pp. 299-306 : 300-304

Urtica pumila sensu Euphras. ex Griseb., Fl. Brit. W.I. 159. 1859, pro syn., non L. 1753. FigS. 1 & 2

Annual, succulent, terrestrial herbs, c. 40 cm tall, monoecious, non-stinging. Roots fibrous, shallow and adventitious off the lower part of stem in contact to soil. Stems erect or decumbent, pellucid, simple or with suppressed, short axillary branches, c. 8 cm long; internodes 4-angled to wavy at base,

Jeomol & Sunojkumar 301

c. 5 cm long, 2–5 mm thick at base, glabrous or with a few short blunt hairs near node, translucent green. Stipules 2, intrapetiolar, free, triangular, c. 0.5 × 0.5 mm, obscure, glabrous, translucent. Leaves opposite-decussate, equal or subequally paired; petioles 2–3.5 cm long, longer than inflorescences, adaxially canaliculate, glabrous except near leaf base, hairs c. 0.4 mm long, translucent; laminae equal or subequal, elliptic or elliptic-ovate or ovate, 2.5–8 × 2–7 cm, basifixed, base cuneate-obtuse, margins bluntly serrate except near base, 3–10 serrations on each sides, apex acute, membranous, sparsely hyaline-strigillose above, glabrous below, lustrous green above, pale green below; venation trinerved, basal lateral veins not curved, evanescent towards apex, lateral nerves 5–7 pairs; cystolith linear, inconspicuous on both surfaces. Inflorescences unisexual, monochasial cymes, male and female crowded in the same leaf-axils, short pedunculed. Staminate inflorescences 0–2 per axils, 0.5–3 cm long, 10–15-flowered, smaller than and at the base of pistillate cymes, the male flowers usually develops and falls-off early, sub-sessile or pedunculate; peduncles 0.5–1.5 mm long, persistent, glabrous, translucent; bracts triangular, c. 0.4 × 0.4 mm, glabrous, translucent, with linear cystoliths. Male buds ovoid from top-view, obovate and compressed from lateral-view, c. 1 mm long, 0.3–0.6 mm in diam., glabrous; pedicels c. 0.5 mm long, glabrous, translucent; tepals 2, c. 0.5 mm long, corniculate, cymbiform, connate about halfway to base, subapical appendage c. 0.1 mm, translucent to greenish; stamens 2; filaments inflexed in bud, translucent; anthers white. Pistillate inflorescences 2–4 per axils, 2–15 mm long, 30–120-flowered; peduncles 1–4 mm long; bracts triangular, c. 0.4 × 0.4 mm, glabrous, translucent, with linear cystoliths. Female flowers c. 0.7 mm long, curved downwards; pedicels c. 0.4 mm long, glabrous, green; tepals 3, strongly unequal, dorsal one large, oblong-cucullate, c. 0.5 mm long, shorter than ovary, green, lateral tepals triangular, c. 0.2 mm long, glabrous, translucent; staminodes 3, scaly, c. 0.5 mm long, shorter than ovary, translucent; ovary ovoid, 0.4–0.5 mm long, stipitate, tubercled, white; stigma pencillate. Achenes ovoid to widely ellipsoid, 0.2–0.5 × 0.2– 0.4 mm, biconvex, length: width ratio 1: 1, slightly curved at apex, muricate, yellow-brown or pale brown with dark brown dots.

Flowering & fruiting: Flowering and fruiting from August to February.

Habitat: On moist, shady mossy rocks, moist vertical earth cuttings, tea plantations and along water courses.

Distribution: Belgium, Central America, Hawaii, Lesser Antilles, Mexico, South America and India.

Specimens examined: INDIA, Karnataka, Kodagu district, Abbi falls [Abbey falls], 28.12.1978, Cecil J. Saldanha, P. Prakash & S.B. Manohar KFP5577 (JCB digital image); Bhagamandala, ± 898 m, 26.10.2016, K.K. Jeomol 151114 ( CALI) ; Cheyandane, on the way to Chelavara waterfalls, ± 979 m, 25.10.2016, K.K. Jeomol 151110 ( CALI) ; Madikeri [Mercara], Kushalnagar , 30.10.1981, Cecil J. Saldanha, B. Gurudev Singh & Shiva Prakash KFP13966 (JCB digital image) . Kerala, Idukki district, Munnar, Lockhart tea plantation, ± 1499 m, 05.09.2019, K.K. Jeomol 169250 ( CALI) ; Painavu , 06.08.2017, K.K. Jeomol 151183 ( CALI) ; Periyar Tiger Reserve, Mlappara , 110 m, 20.11.1998, Jomy Augustine 17911 ( CALI) ; Kozhikode district, Muthapampuzha, Thenpara , ± 576 m, 27.08.2018, Dani Francis 157913 ( CALI) ; Thamarasserry Ghats , 7 th –9 th hairpin, 03.02.2017, K.K. Jeomol 156071 ( CALI) ; Malappuram district, Calicut University Botanical Garden (cultivated, originally from Sulthan Bathery , Wayanad ), 15.11.2019, K.K. Jeomol 169295 ( CALI) ; Wayanad district, Edakkal caves, ± 1100 m, 18.10.2017, K.K. Jeomol 156035 ( CALI) ; Kurumbalakotta , 01.09.2018, K.K. Jeomol 157920 ( CALI) ; Pookode , 750 m, 10.10.1997, M.K. Shyja 52685 ( CALI) ; Ibid. , ± 783 m, 18.10.2017, K.K. Jeomol 156027 ( CALI) ; St. Mary’s College Campus, Sulthan Bathery , ± 925 m, 16.09.2017, K.M. Manudev 156002 ( CALI) ; Thalimala to Chembra peak, 02.11.2017, S. Resmi & K.P. Krishnapriya 156063 ( CALI) ; Thirunelli [Tirunalli], on the way to Brahmagiri , ± 850 m, 18.08.1980, V.S. Ramachandran 68220 ( MH) . Maharashtra, Sindhudurg district, Chaukul , 05.09.2017, K.K. Jeomol 154240 ( CALI) ; Thillari Nagar , 20.09.2018, K.K. Jeomol 157968 ( CALI) . Tamil Nadu, Nilgiris district, Coonoor , 25.01.2017, K. Shinoj & Manu Philip 151166 ( CALI) ; Ooty , ± 2210 m, 26.10.2017, S.Resmi 156052 ( CALI) ; Pambar estate, 900 m, 18.08.1964, J.L. Ellis 20476 ( MH) .

Notes: Pilea hyalina is distinct by its short peduncled inflorescence, invariably 2-tepaled male flower, unequal 3-partite female tepals, sub-oblique, ovoid and muricate, brown achenes. In the Neotropics, the species is considered as a weed and is known outside its native place recently as an invasive species in Belgium and Hawaii, through accidental introduction ( Verloove, 2006; Lau & Frohlich, 2012). Pacific Island Ecosystem at Risk (PIER) by the Institute of Pacific Islands Forestry has listed P. hyalina as a high risk, nursery weed ( US forest service, continuously updated).

The course of the introduction of this species to India is still uncertain. Availability of herbarium specimens 40 years old and considering its occurrence in different areas in Peninsular India, it can be suggested that the species could have been introduced long before as propagules along with other exotic ornamental plants and flourished in humid conditions and got naturalized here. This can be corroborated by the introduction and naturalization of the congener P. microphylla (L.) Liebm. Though not extensively distributed as the latter, the species is propagated by viable seeds.

Figures

Fig. 1. Pilea hyalina Fenzl:a. Habit; b. Flowering twig; c. Leaf base and petiole; d. Node showing hairs; e. braCt; f. Stipule; g. & h. Staminate infloresCenCe; i. & j. Pistillate infloresCenCe; k. Male bud; l. Male flower;m. Female flowers; n. AChenes (a,m & n from K.K. Jeomol 151110; b–f, i & j from S. Resmi & K.P. Krishnapriya 156063; g, h, k & l from Dani FranCis 157913,photos by K.K. Jeomol).

Fig. 2. Pilea hyalina Fenzl:a. Habit; b. Portion of lamina enlarged showing hyaline hairs and petiole; c. Portion of lamina enlarged showing Cystoliths; d. braCts; e. Stipule; f. Staminate infloresCenCe; g. Male bud; h. Male flower; i. Pistillate infloresCenCe; j. & k. Female flowers; L. AChene (a–e & i from S.Resmi & K.P. Krishnapriya 156063,f–h from Dani FranCis 157913; j–lfrom K.K. Jeomol 151110, drawn by K.K. Jeomol).