Impatiens stolonifera Robi & Manudev, 2017

Manudev, K. M., Robi, A. J. & Nampy, Santhosh, 2017, Impatiens stolonifera (Balsaminaceae): A new scapigerous species from the southern Western Ghats, Kerala, India, Phytotaxa 295 (1), pp. 71-76 : 73

Impatiens stolonifera Robi & Manudev sp. nov. ( Figs. 1 & 2 )

Impatiens stolonifera is morphologically similar to Impatiens scapiflora but differs in having a unique stoloniferous habit; strigose, orbicular, fleshy leaves with impressed veins and glaucous dorsally; white flowers with cylindric, conspicuously long and broad spur; mouth with white papillae.

Type:— INDIA, Kerala, Kottayam district, Wagamon hills, ± 1000 m elevation, 18 August 2013, K. M. Manudev & A. J. Robi 135335 (holotype CALI!, isotypes DEV!, MH!, KFRI!).

Scapigerous herbs, up to 30 cm in height. Stem tuberous, 1–2 × 1–2 cm, cream to white, stoloniferous, often connected by the stolons, young roots reddish-brown. Leaves radical, fleshy; petiole 6–15 cm long, glabrous, channeled at upper side, rounded at lower side; lamina 4–8 × 4–6.5 cm, orbicular or rounded, cordate at base, rounded or mucronate at apex, margin distantly serrate, strigose above, glabrous and glaucous below; lateral veins 5–8 pairs, prominently impressed above, faint below. Scapes racemose, 30–45 cm long, glabrous, erect, 6–20 flowered. Flowers distally oriented, white with white patches of papillae near the centre; bracts broadly ovate, 3.5–4 × 2–3 mm, concave, pale green, glabrous; pedicels 2–4 cm long, glabrous, elongating in fruiting stage; lateral sepals 3.5–5.5 × 3.5–4 mm, ovate, entire, glabrous, green or pale green with purple spots; lower sepals broadly elliptic, spurred; spur incurved, cylindric, 5–7 cm long, c. 3.5 mm wide, with an anterior invagination, white, glabrous; dorsal petals triangular, 1–1.2 × 1.2–1.5 cm, saucer shaped, not lobed, margins entire, glabrous; lateral united petals 3-lobed, non-auricled, 3–4 cm long, 2–2.5 cm wide, white with a tuft of white papillae a little above the base of the inner margin; basal lobes largest, 2.5–3 cm long, bent upwards, broadly oblong; middle lobes 2.5–3 cm long, oblong to broadly obovate, straight with truncate tip; distal lobes narrow, straight with obtuse tip, 2.5–3 cm long. Stamens 5, connate; filaments white to greenish white. Ovary broadly ellipsoid, 5–7 mm long, 2.5–5 mm wide, yellowish greenish, acute at apex, glabrous. Capsule broadly ellipsoid, acute, 1–2 cm long, glabrous, greenish or brownish; seeds minute, tuberculate, with a dense tuft of hairs.

Etymology:—The specific epithet refers to the stoloniferous habit of the species, which is a unique character seen in South Indian species of Impatiens .

Notes:—This species closely resembles I. scapiflora from which it can be distinguished in having a unique stoloniferous tuber; fleshy strigose leaves with glaucous adaxial side and impressed veins; white flowers with conspicuously long and broad spur; mouth with white papillae. A stoloniferous tuber is of rare occurrence among the scapigerous species of Impatiens in India. Mature plants of this taxon produce long multiple stolons upon which new plantlets are developed at the nodes. The newly formed tubers are often interconnected by these stolons. This character is very distinct among the species of Impatiens in southern Western Ghats which is so far reported only in I. clavicornu and I. tirunelvelica . However the latter taxa can be readily distinguished by their shorter saccate or pouch like spur of the dorsal sepal which is not longer than the united petals. A comparative morphological account of I. stolonifera with its allied taxa is given in Table 1.

Distribution & ecology:— Impatiens stolonifera grows in wet water dripping rock crevices among the grasses at elevations of 1,000 –1,500 m, associated with Cucumis silentvalleyi ( Manilal, Sabu & Mathew 1985: 283) Ghebretinsae & Thulin (2007: 178) , Sonerila rotundifolia Beddome (1861: 74) , Sonerila wallichii Bennett (1844: 215) , Henckelia bracteata Janeesha & Nampy (2015: 53) , Impatiens herbicola Hooker (1911: 354) , Phyllocephalum scabridum (DC. 1834: 7) Kirkman (1981:10) , etc.

Phenology:—Flowering from July with peak in August; fruiting in August–September.

Additional specimen examined (Paratype):— INDIA. Kerala: Kottayam District, Wagamon hills, ± 1000 m, 18 August 2015, A.J. Robi 28081 (KFRI!).

Conservation status:— Impatiens stolonifera is so far known from the type locality only. About 75 individuals were located in two populations at the type locality. According to IUCN criteria, the species falls under the category Data Deficient (DD) ( IUCN 2001, 2010).

Figures

FIGURE 1. Impatiens stolonifera: A. Population of I. stolonifera growing in wet rock crevices at the type locality; B. A plant with scapes; C. A young plant with long stolons that bear plantlets at their nodes; D. A young plant arising from the node of stolon with reddish roots; E. Subterranean tubers connected by stolons (Photos by K. M. MANUDEV).

FIGURE 2. Impatiens stolonifera: A. Leaf-abaxial side; B. Leaf-adaxial side; C. Strigose hairs on the abaxial side; D. Bracts; E. Flower bud; F. Dorsal sepals with spur; G. Cross section of spur; H. Lateral sepals; I. Dorsal petal; J. United petals; K-M. Connate stamens; N. Ovary; O. Stigma; P. Capsule; Q & R. Seeds enlarged (Photos by K. M. MANUDEV).