Calamagrostis nagarum (Bor) G.Singh in Taxon 33(1): 94 (1984); Shukla, Grass. N. E. India, 47 (1996)

Prasad, Dileshwar, Kumar, Ravindra, Jaiswal, Shubham, Yadav, Rekha, Tiwari, Smita & Agnihotri, Priyanka, 2022, An update on the taxonomy of Calamagrostis nagarum (Bor) G. Singh and its allies (Poaceae, Agrostidinae): morphometrics and micro-morphology, PhytoKeys 212, pp. 135-155 : 135

Calamagrostis nagarum (Bor) G.Singh in Taxon 33(1): 94 (1984); Shukla, Grass. N. E. India, 47 (1996)

Deyeuxia nagarum Bor in Indian Forest Rec., Bot. 1: 69 (1938); Bor, Fl. Assam, 5: 145 (1940); Bor, Grass. Burma, Ceylon, India & Pakistan, 399 (1960). Basionym.

Type.

India. Nagaland [earlier in Assam], Naga hills, Japvo range, 9,500 ft [2895 m], September 1937, NL Bor 2834 (holo. K: K000032378, digital image!) .

Amended description.

A perennial, rhizomatous, robust grass, 50-100 cm tall. Culms 40-80 cm long, simple, terete, glabrous, 2-3 nodes below the panicle. Node glabrous, compressed. Leaf sheaths split, overlapping, loose, connate toward base, smooth, sometimes scaberulous. Leaf blades 7-20 × 0.3-0.7 cm, flat, narrowly-linear, adaxial scabrous with distantly pilose and abaxial surface scabrous; apex attenuate; margin scabrid. Ligules 0.75-4.2 mm long, membranous, adaxial surface glabrous, abaxial surface scabrous; apex obtuse, lacerate. Inflorescence a panicle, 5-18 × 5-8 cm, very lax with spreading branches; lower panicle branches paired or in whorls of 3-5; 1-8 cm long, almost smooth or sometime scabrous, filiform, flexuous. Rachis slender, glabrous or scabrous. Spikelets 5.1-6.7 × 1.5-2 mm, lanceolate to wedge shaped at maturity, bearing 1-floret, disarticulating above the glume and below the floret, greenish with pink tinged; glumes subequal, persistent; floret hermaphroditic. Pedicel shorter than spikelet, slender, scabrous. Lower glume 3.7-5.2 × 0.65-1.3 mm, 1-nerved, 1-keeled, lanceolate, greenish with pink tinge near margin, scaberulous to somewhat glabrous; apex acuminate; margin narrowly hyaline, entire; keel scabrous. Upper glume 3.8-5.4 × 0.87-1.34 mm, 3-nerved, 1-keeled, lanceolate, greenish with pink tinged, scabrous; apex acuminate; margin narrowly hyaline, entire; keel scabrous. Callus evenly bearded, hairs 1.1-1.9 mm long, nearly half of the length of lemma or shorter. Lemma 3.1-4.3 × 1.0-1.6 mm, 5-nerved, membranous, surface scaberulous with papillate, awned; apex acute with 4-nerve prolongation 0.27-0.9 mm long; margin hyaline. Rachilla 1.2-1.9 mm long, penicillate hairy, usually bare at base; rachilla with hairs 2.5-4.9 mm long. Awn 2.8-5.1 mm long, straight, filiform, slender, scabrous-antrorse, exerted from the spikelet, arising from above the middle of lemma back. Palea 1.8-2.7 mm long, 2-nerved, 2-keeled, hyaline-membranous, rounded on back; apex slightly bifid. Lodicules 2, 0.7-0.8 mm long, lanceolate. Stamens 3; anthers 1.5-2.3 mm long, narrowly linear. Mature caryopsis not seen.

Phenology.

September to October (flowering and fruiting).

Habitat and distribution.

Calmagrostis nagarum was discovered in the Japvo range of Naga Hills situated in Nagaland, which is geographically located in the eastern region of Assam, southernmost of Arunachal Pradesh and northern Manipur, India and close to the political boundary of Myanmar. Approximately 3% of the total geographical region of Nagaland is part of the Himalayan region, while the rest of the region is situated in a complex mountain system forming Naga Hills. Previously, it was only known from the type locality in a sub-temperate region at about 2800 m elevation and was considered to be endemic for that geographic range ( Bor 1938, 1940, 1960; Shukla 1996). Later, it was recorded from Bhutan, geographically located in Eastern Himalayas, by Noltie (2000), where it was found not only on damp shady cliffs in blue pine and oak forest but also in riverbanks and scrubland, at 2400-2840 m elevation. Recently, it was documented in an updated checklist of grasses of Uttarakhand, Western Himalaya ( Kandwal and Gupta 2009), but this geographic range was not included by Kellogg et al. (2020) as part of the species distributional range. During the present study, we collected specimens of C. nagarum from Pindari Valley, located in Bageshwar district of Uttarakhand, and confirmed its occurrence in Western Himalaya (Fig. 5 ). It was found growing in Danthonia grassland in association with Polygonum sp., Anagalis sp., and Gaultheria sp., at 3000-3050 m elevation in Phurkia village and, in Dhakuri top at about 2900 m elevation on forest margin as well as on Pindar riverbank in Dwali village at 2500-2800 m elevation. The vertical distribution shows C. nagarum is mainly confined to 2500-3100 m elevation, below the tree line, at about 3,300 m elevation, whereas C. lahulensis is widely distributed above the treeline at about 3350-4200 m elevation, which overlaps with the elevation range of C. scabrescens (Fig. 6 ).

Taxonomic notes and allied species.

Calamagrostis nagarum should be placed in C. lahulensis - C. scabrescens complex because of its rachilla with penicillate hairs equal to longer than lemma, callus hairs shorter than half of the lemma and awn inserted at about middle to tip of the lemma. Within this complex, it should be recognized by the presence of pilose hairs on adaxial surface of leaf blade, widely spreading panicle branches, nerve prolongation of lemma (0.3-)0.4-0.7(-0.9) mm long and filiform awn within this complex (Figs 7 , 8 , 9 ). Calamagrostis nagarum is more similar to C. lahulensis than to C. scabrescens . It differs from C. lahulensis in panicle length [(5-)8.1-12(-18) cm long vs. (1.5-)4-7(-9) cm long], lower branches of panicle [spreading with (1.0-)3-7(-8) cm long vs. ascending with (0.5-)1-3(-3.5) cm long] and, from the latter in culm (glabrous vs. scabrous), ligule length [(0.75-)0.83-1.2(-1.36) mm long vs. (3.6-)4.9-7.1(-8.84) mm long], lower glume width [(0.65-)0.81-1.1(-1.3) mm long vs. (1.1-) 1.3-1.5 (-1.7) mm long)] and awn length [(1.6-)2.3-3.2(-5.7) mm long vs. (3.3-)5.1-6.8(-7.9) mm long]. Calamagrostis nagarum is somewhat similar to another member of this complex, C. nandadeviensis , in having (5-)8.1-12(-17) mm long panicles, but differs from the latter in culm pubescence (glabrous vs. scabrous), ligule length [(0.75-)0.83-1.2(-1.36) mm long vs. (6.1-)6.5-7.5(-8.1) mm long], upper glume nervation (3-nerved vs. 1-nerved) and ratio of palea length to lemma length [(0.49-)0.54-0.62(-0.72) vs. (0.75-)0.77-0.85(-0.90)]. Along with this, C. himalaica (L.Liu ex Wen L.Chen) Paszko, reported from China and Myanmar, and C. nyingchiensis (P.C.Kuo & S.L.Lu) Paszko, restricted to China ( Paszko 2015; Paszko 2016) are also members of the C. lahulensis - C. scabrescens complex. C. nagarum differs from C. himalaica in awn (2.8-5.1 mm long, straight and filiform vs. 4.5-10 mm long, strongly geniculate) and from C. nyingchiensis in anther length (1.5-2.3 mm long vs. 0.7-1.1 mm long). Calamagrostis nagarum differs from C. elatior by having callus hairs shorter than half of the length of lemma and, straight and filiform awn.

Figures

Figure 5. Geographic distribution of Calamagrostis nagarum.

Figure 6. Box plot for vertical distribution of C. lahulensis, C. nagarum and C. scabrescens.

Figure 7. Calamagrostis nagarum: A habit B panicle C leaf blade and panicle. [Photos were taken through Samsung F 41 by the first author, correspond to D. Prasad et al. 339372].

Figure 8. Calamagrostis nagarum: A culm and ligule B Panicle C lower panicle branch D leaf blade, adaxial view E ligules. [Photographs: A-C from Prasad et al. 339324 and D-E from D. Prasad et al. 339372].

Figure 9. Calamagrostis nagarum: A spikelet B remove glumes C floret D, E Open floret F, G lemma, H lemma apex I, J rachilla, K, L palea M anthers N lodicules O caryopsis. [Photographs: A-E, H-I and L-O from D. Prasad et al. 339324 and F-G and J-K from D. Prasad et al. 339372].