THE BAMBOOS OF NEPAL AND BHUTAN PART II : Arundinaria , Thamnocalamus , Borinda , and Yushania ( Gramineae : Poaceae

This paper continues the systematic treatment of the bamboos of Nepal and Bhutan, covering four hardy temperate genera with semelauctant inflorescences and 3 stamens from the subtribe Arundinariinae Bentham. Arundinaria Michaux has leptomorph rhizomes, while Thamnocalamus Munro, Yushania Keng f., and the new genus Borinda have pachymorph rhizomes. The separation of these and related Sino-Himalayan genera is discussed. Sinarundinaria Nakai is treated as a synonym of Fargesia Franchet, a genus that is not known from the Himalayas. A new treatment of Himalayan Thamnocalamus species is given, including the description of two new subspecies of Thamnocalamus spathiflorus (Trin.) Munro, subsp. nepalensis and subsp. occidentalis, and one new variety, bhutanensis. T. aristatus is treated as a synonym of T. spathiflorus subsp. spathiflorus, and Fargesia crassinoda Yi is transferred and given new status as Thamnocalamus spathiflorus (Trin.) Munro var. crassinodus (Yi) Stapleton. Two new species of Borinda are described: B. chigar from West Nepal and B. emeryi from East Nepal. Six species of Fargesia from Tibet are transferred to Borinda, which thus comprises eight species.


STATUS AND SEPARATION OF THE GENERA
Bamboos from the mountains of the Indian subcontinent and China with 3 stamens and terete culms were all placed in Arundinaria Michaux until late in the 19th century, when two genera for bamboos with spathate inflorescences were described.Munro (1868) described Thamnocalamus as a Himalayan genus with groups of one to four racemes at the tips of branchlets, each raceme being enclosed in a spathe.Franchet (1893) described Fargesia as a Chinese genus with spikelets grouped together in a single unilateral cluster enclosed in a spathe.Although Gamble (1896) reduced Thamnocalamus to a synonym of Arundinaria, it has been recognized consistently by subsequent authorities.Fargesia has received less recognition.Keng (1983) and Soderstrom & Ellis (1987) recognized it as a separate genus, but Clayton & Renvoize (1986) and Chao & Renvoize (1989) treated it as a synonym of Thamnocalamus.
The large group of Sino-Himalayan bamboos with simple, open, semelauctant inflorescences without enclosing spathes has also received conflicting treatments.The possession of leptomorph (monopodial or amphipodial) rhizome axes is now widely accepted to be an important characteristic in the bamboos.In this group of bamboos such rhizomes are found only in Arundinaria Michaux and Chimonobambusa Makino.All other bamboos have determinate pachymorph (sympodial) rhizomes and a substantially higher number of branches, and all authorities would agree that there is a large group of species that cannot be accommodated in Arundinaria, Chimonobambusa, or Thamnocalamus.This group is characterized by the combination of simple, unspathed, loose inflorescences, pachymorph rhizomes, and several branches.Nakai (1935) described Sinarundinaria for two Chinese bamboos cultivated in the west that apparently came from this broad group, S. nitida and S. murielae, and the genus became widely recognized.Nakai's description was inaccurate, however, attributing the genus incorrectly with leptomorph rhizomes and multiple branch buds, and it did not cover the flowers, which were not known at that time.Sinarundinaria murielae Nakai began to flower in the 1970s.The flowers were spathed and similar to those of the type species of Fargesia, F. spathacea.Fargesia was considered at that time to be a synonym of Thamnocalamus (Soderstrom, 1979a), and S. murielae was consequently transferred to Thamnocalamus as a synonym of T. spathaceus (Soderstrom, 1979b), although Soderstrom later recognized Fargesia as a separate genus (Soderstrom & Ellis, 1987).The flowers of the type species, S. nitida, remained unknown, however, and several authorities continued to place most species with 3 stamens, pachymorph rhizomes and loose semelauctant inflorescences in Sinarundinaria.
Several other genera of 3-stamened, pachymorph-rhizomed bamboos with loose inflorescences have been described in China.These genera have all been treated as synonyms of Sinarundinaria by those who have recognized that genus.The first genus to be described after Sinarundinaria was Yushania Keng f., with type species Y. niitakayamensis from Taiwan, a species with open inflorescences and pachymorph rhizomes with very long necks.Chao et al. (1980) argued vigorously for the treatment of Yushania as a synonym of Sinarundinaria, a treatment followed by Clayton & Renvoize (1986) and Chao & Renvoize (1989).
The initiation of flowering in 1993 of the type species of Sinarundinaria, S. nitida (Renvoize, 1993), has eventually confirmed that this species is also congeneric with the type species of the earlier genus Fargesia (Franchet, 1893), having unilateral spathed inflorescences similar to those of both Fargesia spathacea and Sinarundinaria murielae.Most authorities who recognized Sinarundinaria clearly considered Fargesia to be a synonym of Thamnocalamus, and would presumably now treat both Fargesia and Sinarundinaria as synonyms of Thamnocalamus.However, this would make the genus large and extremely heterogeneous.Demoly (1991) continued to include Fargesia (with its new synonym Sinarundinaria) in Thamnocalamus, while also recognizing other Chinese genera such as Yushania.However, this is still not very satisfactory, as Thamnocalamus and Fargesia can be clearly separated on a range of floral and vegetative characteristics.Other authorities (Keng f., 1957;Keng f., 1982a;Keng f., 1982b;Keng f., 1983;Yi, 1983) have adopted a much narrower generic concept, latterly recognizing both Fargesia and Yushania as well as many other smaller genera, and treating Sinarundinaria as a synonym of Fargesia.Campbell (1988) attempted a compromise between the different approaches, which resulted in the recognition of Sinarundinaria in two parts in addition to both Fargesia and Yushania, but circumscription of the smaller genera and groups became very difficult.
In an attempt to delimit Sino-Himalayan genera more satisfactorily a range of morphological characters have been considered.Previously reported studies (Stapleton, 1991) showed that characteristics of vegetative branching and sheathing were particularly useful at the generic level in these bamboos, and could be used to separate distinct groups of species, which matched several new genera recently described in the Chinese literature.Very close similarities were seen between Fargesia murielae and Sinarundinaria nitida in branching and prophyll characteristics, and consequently Sinarundinaria was treated as a synonym of Fargesia.This treatment was borne out when S. nitida eventually flowered, illustrating the predictive value of  these vegetative characteristics at the generic level.Species of Thamnocalamus were seen to be clearly and unambiguously distinct from those of all the other 3-stamened Himalayan genera, including Fargesia.The mid-culm branch prophyll in Thamnocalamus has two keels (see Fig. 1a) and all branch axes are subtended by sheaths.In the type species of other genera such as Fargesia, Yushania and Sinarundinaria, the mid-culm branch prophyll has only one keel, and branch axes lack subtending sheaths (see Fig. 1b).Floral features such as degree of reduction of branches or sheaths subtending branching within the inflorescence, and presence of vestigial buds in glume axils, reinforced vegetative differences between Thamnocalamus and the other genera.
The genera that were distinguished clearly on a range of characters included Fargesia Franchet, Yushania Keng f., Ampelocalamus Chen, Wen, & Sheng, Himalayacalamus Keng f., Drepanostachyum Keng f., and Neomicrocalamus Keng f.None of these genera were recognized by Clayton & Renvoize (1986) or Chao & Renvoize (1989).In addition to those groups of species that can be placed satisfactorily within published genera, a further group of species can be distinguished on a range of floral and vegetative characteristics.These species have open paniculate inflorescences, similar to those of Yushania but with more bracts and fewer pulvini at points of inflorescence branching.Their rhizomes are shorter than those of Yushania species, and closer to those of Fargesia species, but the buds and branching are borne well above the nodal line on a projection similar to that described by McClure (1973) as a 'promontory' in species of Arthrostylidium Ruprecht.Basal culm buds are closed at the front while they are always open in Yushania.As no published genus appears appropriate for these species, the new genus Borinda is described.It includes several little-known Tibetan bamboos, for example Arundinaria macclureana Bor, and two new species from Nepal.The genus is named in honour of Dr N.L. Bor, the author of the first species described.The characteristics of Borinda and related genera are given in Table 1.Fargesia, as interpreted here, is not known from the Himalayas, apparently being confined to the mountains of central China.

SYSTEMATIC TREATMENT
The numbering of genera continues from Part I (Stapleton, 1994).All specimens cited are at K unless otherwise indicated.The abbreviation THIM has now been registered with the Index Herbariorum for the Forest Department Herbarium in Thimphu (previously referred to as THIMPHU).
Subtribe Arundinariinae Bentham, J. Linn.Soc.(Bot.)This genus has been gradually reduced by recognition of new genera to the point where it has been considered a monotypic North American genus (Keng & Keng f., 1959), but the characteristics of the type species have been clearly defined (McClure, 1973), and it is difficult to see how some Asian genera such as Pleioblastus Nakai can be separated from it consistently.Arundinaria includes only one Himalayan species.The combination of leptomorph rhizomes, which can continue under the ground indefinitely, and tall 2-keeled mid-culm bud prophylls separate this genus from all other Himalayan genera.

Thamnocalamus
Frost-hardy bamboos from upper temperate zones.Clumps unicaespitose, rhizomes pachymorph with necks less than 25cm long.Inflorescence semelauctant, a dense contracted racemose panicle or raceme, never unilateral, with occasional fasciculation and no pulvini, branches usually subtended by substantial sheaths or occasionally by rings of hairs, and prophylls on the branches represented by single-keeled sheaths inserted near the point of branching or as the lower glumes of pedicellate spikelets, which often subtend vestigial buds.Mid-culm branch buds enclosed by single 2-keeled prophylls, the front of all culm buds open, with lateral branch axes always subtended by sheaths, first-year branches usually 5 at the mid-culm nodes.Leaf venation strongly tessellated.
HIMALAYAN TAXA Three species of Thamnocalamus have been described from the Himalayas.The type species, T. spathiflorus (Trin.)Munro, was described from material collected by Wallich in Nepal in 1821.Munro (1868) included sterile material from north-western India and Sikkim under this species, albeit with reservations.Flowering material was later collected in north-western India and Sikkim by Gamble and others. Gamble (1896) considered the Himalayan material to represent two separate species.He assumed the Wallich 1821 type collection of spathiflorus had come from western Nepal, and cited it (Gamble, 1896), along with the material from northwestern India, under Arundinaria spathiflora Trin.He described a new species, Arundinaria aristata Gamble, from the material collected in Sikkim.However, it would appear that the Wallich 1821 type collection of T. spathiflorus is most likely to have been made in central rather than western Nepal.Firstly, Wallich could not leave the Kathmandu area (Burkill, 1953), and most of his collections and those of his collectors came from central Nepal.Secondly the Wallich 1821 type collection has oral setae on some of the leaves, while all Nepalese collections of T. spathiflorus from west of the Kathmandu Valley have leaf sheaths without oral setae.If this supposition is correct it would place the type collections of both T. spathiflorus and T. aristatus in the same subspecies.This is supported by further collections of material that was flowering at approximately the same time, clearly labelled E. Nepalia, with flowers apparently identical to the Wallich 1821 type material.These were presumably made in 1818 by Wallich's Kathmandu-based collectors prior to his own residence in Kathmandu.Therefore it would seem that Gamble was incorrect in placing Wallich's type material in a different species to material from Sikkim, and that Arundinaria aristata Gamble is a synonym of Thamnocalamus spathiflorus (Trin.)Munro.A third Himalayan species, Thamnocalamus falconeri Munro, is treated here as Himalayacalamus falconeri (Munro) Keng f.Considerable variation in vegetative characteristics is encountered along the Himalayan distribution of Thamnocalamus.Three taxa are known to cover broad geographical areas and can be distinguished consistently on important vegetative characteristics.They are treated here as subspecies spathiflorus from central and eastern Nepal, Sikkim, and Bhutan, the new subspecies nepalensis from central and western Nepal, and the new subspecies occidentalis from north-western India.Although there are some minor differences between the flowers of these subspecies, such differences are obscured by the considerable variation found within each taxon, and it seems impossible to distinguish between their flowers consistently.Therefore all taxa described from the Himalayas are treated here as one species, Thamnocalamus spathiflorus (Trin.)Munro.
Two further taxa are known from localized areas.One has distinctive culm sheaths and culms, and is presently known only from central Bhutan.It is described here as a new variety, bhutanensis.Collections of Thamnocalamus spathiflorus from eastern Bhutan have not included culm sheaths, so the extent and status of this taxon are both uncertain at the present time.The other taxon was described as Fargesia crassinoda Yi from material collected in Tibet.It has also been collected from an adjacent area of Nepal, and plants are now in cultivation in Europe.Although its flowers are not known, the vegetative branching shows its affinity to Thamnocalamus rather than Fargesia.It is transferred and given new status here as T. spathiflorus var.crassinodus.It has only been found on the geographic boundary between the two subspecies, spathiflorus and nepalensis, and collections combine characteristics of both subspecies.Growth is vigorous and the culm nodes are swollen.The culm sheaths may be completely glabrous, or they may have light or dense bristles.Although leaf size is variable, several collections appear to have substantially smaller leaves than those of subspecies spathiflorus or nepalensis.Local name: jarbutto (Nepali).
Differing from the type subspecies in its glabrous culm sheaths and its leaf sheaths without oral setae.Distribution: Western zones of Nepal to Gosainkund and adjacent Tibetan valleys.Local name: ringal.
Similar to Thamnocalamus spathiflorus subsp.spathiflorus, but differing in its glabrous asymmetrical culm sheaths, and shorter hairs on the leaf sheath callus (outer ligule).Distribution: North-western Himalayas of Himachal Pradesh and Uttar Pradesh.Local name: hum (Dzongkha).
Similar to Fargesia Franchet, but differing in its loose paniculate inflorescences with hairs and sometimes pulvini at the points of branching, margins of the buds usually not fused at the front, and greater number of branches, inserted above the nodes.To be distinguished from Yushania Keng f. by the shorter rhizomes and the more contracted panicles.Type species: Borinda macclureana (Bor) Stapleton.
Frost-hardy bamboos from middle to upper temperate zones.Clumps unicaespitose, rhizomes pachymorph with solid necks less than 30cm long, culms basally curving when rhizome necks are long, surface usually finely ridged.Inflorescence semelauctant, an open more or less contracted panicle, branches single with no fasciculation and few pulvini, branching subtended by very small remnants of sheaths or rings of hairs, and prophylls on the branches represented by single-keeled sheaths inserted near the point of branching or as the lower glumes of pedicellate spikelets.Culms unarmed.Mid-culm branch buds inserted above node on small raised promontory, enclosed by two single-keeled bracts, the front of the buds open, with lateral branch axes replicated without subtending sheaths, usually giving 7 branches at the mid-culm nodes in the first year.Basal 1-4 culm buds closed at front by fusion of margins.Leaf venation strongly tessellated.
PREVIOUSLY DESCRIBED SPECIES Bor (1958) described Arundinaria macclureana from material collected in Tibet, and this species is now chosen as the type species of the new genus Borinda.Five species of Fargesia described by Yi (1983) from sterile Tibetan material collected in areas substantially to the east of Bhutan and Nepal are also considered here to be members of this genus.Several of these species seem to overlap morphologically, but a sound revision must await further fieldwork and collection of flowering material in Tibet.No species with characteristics of Borinda have hitherto been described from within Nepal, Sikkim, or Bhutan.

SPECIES ENCOUNTERED IN NEPAL AND BHUTAN
Three species of Borinda have been encountered in Nepal and Bhutan.Two are clearly distinct from the species described from Tibetan material: Borinda chigar from western Nepal, and Borinda emeryi from eastern Nepal.Both these new species seem to be localized and they are of little importance in the rural economy.The third species, Borinda grossa (Yi) Stapleton, is common across central Bhutan, where it is a very important minor forest product, widely harvested from the forest and also cultivated for production of roof mats and fences.
Borinda grossa is similar to B. macclureana and also to two species known only from Tibet, and here transferred to Borinda, B. glabrifolia and B. setosa.The glumes and paleas of B. grossa are longer and more pubescent than those of B. macclureana, with margins and keels that are more ciliate, and they are arranged in longer, more flattened spikelets.Leaf sheath auricles are scarce to absent in B. grossa, while B. macclureana has prominent auricles.The oral setae of B. grossa are glabrous, while those of B. macclureana are densely scabrous.Unfortunately the culm sheaths of B. macclureana and the flowers of B. glabrifolia and B. setosa have not been collected.More comprehensive collections of Tibetan material are required before the correct status of these taxa can be decided upon.Munro wrote the name 'Thamnocalamus bhotanica' on a Griffith collection of B. grossa from Bhutan, but cited the specimen under Thamnocalamus spathiflorus (1868).Yi used two infertile specimens collected in Tibet to describe the species (as Fargesia grossa), relating it to Arundinaria racemosa Munro (as Fargesia racemosa (Munro) Yi).A flowering specimen found in Bhutan in 1986 is described below.
Borinda emeryi is more clearly distinct from all the Tibetan species, having glabrous culm sheaths and narrower florets.Collections had been determined (Chao & Renvoize, 1989) as Sinarundinaria pantlingii (Gamble) Chao & Renvoize (Yushania pantlingii (Gamble) Majumdar).It has persistent wax covering the entire culm internode, which becomes black with age.Leaf sheaths and branchlets also become very dark from exposure to frost.This leads to the local name 'black bamboo'.Present collections are inadequate for detailed illustration.
Borinda chigar is an unusual and interesting species found initially on the southern flank of the Annapurna massif in western Nepal (Stapleton & Tamrakar, 1983).The specific epithet is based upon its vernacular name in Kaski district.It is distinctly different from all other Himalayan species in its extraordinarily long ligules on both culm and leaf sheaths.The bud characters seem to place it in Borinda, but only very small buds have been collected and its flowers are not known.It also differs from all the Himalayan species known so far in having delicate culm sheaths without clearly defined blades, very small branches and extremely narrow leaves.The culms sweep outwards at the base, giving an open form of clump.Local name: chigar (Nepali).
Well distinguished from all the known species of the genus by its very long ligules, its narrow leaves, its basally upward-curving culms and its thin culm sheaths.Inflorescence not known.
Clumps open.Rhizome pachymorph, up to 30cm long, solid.Culms apically drooping, basally curving outwards and upwards; height up to 4m; at c.50cm above ground diameter up to 1.5cm, walls up to 2mm thick; nodes slightly raised, persistent sheath base lightly white-pubescent at first, unarmed; maximum internode length 15cm; surface with very dense white wax over entire internode, culm remaining dull.New culm sheath from c.50cm above ground c.75mm wide at base, height to ligule c.27mm, attenuating triangularly from base; upper ½ membranous, disintegrating rapidly, transverse veinlets prominent; blade always erect, c.3cm long × 5mm wide, very persistent, interior very shortly pubescent beside ligule; hairs scattered to quite dense, erect, clear, with bulbous bases; shoulders and auricles absent, blade continuous with sheath; oral setae absent; ligule triangular to subulate, margin sparsely ciliate or penicillate; upper ½ of both edges with rather sparse, stout, brittle cilia <1mm long.New leaf sheath surface glabrous, margins glabrous; callus (outer ligule) not pronounced, with cilia up to 1mm long; auricles none; shoulders rising very steeply, shortly ciliate; oral setae none; ligule extremely long, up to 5mm, glabrous, ragged.Leaf blade up to 110mm long × 6mm wide; abaxial and adaxial surfaces glabrous and glaucous; petiole glabrous, narrow, long; tessellation distinct, but transverse veinlets well spaced out; base attenuate.Branches small, from elliptical buds with broad, rounded wings; central branch up to 1mm in diameter with no aerial roots.Inflorescence not known.Distribution: Apparently endemic to central and western Nepal.Local name: kalo nigalo (Nepali).

Borinda emeryi
Similar to Borinda macclureana but with nearly glabrous culm sheaths, leaf sheaths without oral setae, and narrower glumes shortly pubescent or glabrous towards their margins.

Borinda extensa
Similar to Borinda macclureana but larger, with longer glumes and paleas, both with shorter pubescence, leaf sheaths without auricles, oral setae on the leaf sheaths glabrous.
Clumps dense.Rhizomes pachymorph, up to 30cm long, solid.Culms drooping, maximum length 10m; at c.50cm above ground maximum diameter 4.5cm, walls up to 5mm thick, nodes not substantially raised, unarmed; maximum internode length 50cm; surface finely ridged, ± wax, entire internode often covered with wax, new culms often strongly glaucous and densely waxy below nodes.New culm sheath from c.50cm above ground up to 12cm wide at base, attenuating triangularly and convexly to a width of up to 1cm at the neck, persistent till branching; height to ligule c.26cm; bristles scattered, deciduous, brown, bulbous-based, antrorsely erect, c.1mm long; blade decurrent, erect at tip of new shoot, up to 70mm long, c.2mm wide, lightly covered with c.0.5mm deciduous bristles, edges scabrous, quickly deciduous; base pubescent or pilose with ring of slender 2-3mm light brown hairs; shoulders with c.0.2mm cilia, bearing setae at edges; auricles absent on basal sheaths to very small at shoot apex; oral setae 6-10 each side, 3-8mm long, thick, erect, straight, honey-brown, glabrous with fine spiralling striations, extending onto edges of sheaths near culm base; ligule 1-2mm long, shortly fimbriate, densely 0.3-0.5mmpubescent, concave or truncate, or convex and asymmetrical at culm base with one end extending down the sheath margin; edges with c.1mm-long cilia, overlapping edge ciliate to base, distal ¼ of inner edge ciliate, cilia merging with oral setae on sheaths from base of culm.New leaf sheath with light c.1mm-long pubescence at first (proximal sheaths) or glabrous (distal sheaths); margins glabrous; callus (outer ligule) not pronounced, but with prominent cilia up to 1mm long and initially cinnamon-coloured at the edges and c.0.2mm long and white at the centre; auricles absent or minute; shoulders with c.0.1mm-long cilia; oral setae 2-5 each side, wavy, erect, glabrous, 3-5mm long and often fused at the base; ligule 15-25mm long, c.0.1mm puberulent, truncate.Leaf blade 4.5-18(-26)cm long, breadth 5-20(-25)mm; abaxial lightly to densely and persistently pilose all over with c.1mm-long soft hairs, adaxial glabrous; petiole abaxial with dense c.1mm-long hairs, adaxial proximally pubescent with <0.3mm hairs; tessellation distinct.Branch buds present at all nodes, 1.5-3cm tall, narrow, above 2-5mm-long swelling; basal bud dorsally and ventrally closed; mid-culm branches 5-7 in first year, up to 16 branches later; central branch up to 3mm in diameter, with no aerial roots.Inflorescence semelauctant, a panicle usually with rings of hairs subtending BAMBOOS OF NEPAL AND BHUTAN II Frost-hardy bamboos from middle to upper temperate zones.Stands diffuse, rhizomes pachymorph with necks up to 2m long.Culms basally erect, surface often scabrous, usually not ridged.Inflorescence semelauctant, an open panicle, often with pulvini but with little or no fasciculation.Panicle branches subtended by very small remnants of sheaths or rings of hairs, with branch prophylls represented by the lower glumes of pedicellate spikelets.Mid-culm branch buds inserted above node on small raised promontory, enclosed by two single-keeled bracts, always open.Lateral branch axes replicated without subtending sheaths.Basal culm buds open at front.Leaf venation strongly tessellated.

GENERIC STATUS AND SEPARATION
This genus was established specifically for temperate bamboos with widely spreading habit but pachymorph rhizomes.It is now universally accepted that these species are clearly separated from the genus Arundinaria, which has leptomorph rhizomes that can continue underground growth indefinitely, and is represented in the Himalayas by a single species, A. racemosa Munro. Keng (1982b) described a new genus, Butania, with type species Butania pantlingii (Gamble) Keng f., described from material collected in Sikkim.This was keyed out (Keng f., 1982a) from Yushania and Fargesia on the assumption that, like Chimonocalamus and Chimonobambusa, it has thorns and 3 branch buds at each culm node.This may have been because of Gamble's suggestion (Gamble, 1896) that his Arundinaria pantlingii might turn out to be close to the thorny, clump-forming species from Meghalaya and Sikkim, Chimonocalamus griffithianus (Munro) Hsueh & Yi.Gamble (1912) re-iterated that his A. pantlingii might be thorny at the nodes, but the collections of A. pantlingii from Sikkim have no evidence of thorns whatsoever, and they clearly have more than three branches.The flowers are very close to those of Yushania maling, with the large inflorescence pulvini seen in many Yushania species, and Majumdar (1989) in his enumeration of Indian bamboos transferred this species to Yushania.Collections of A. pantlingii from Sikkim do not include rhizomes, but the bamboo tentatively identified as Yushania pantlingii in eastern Bhutan has spreading, long-necked pachymorph rhizomes, similar to those of Yushania hirsuta.Gamble cultivated his Arundinaria pantlingii at his house in Hampshire from material sent from the Lloyd Botanic Garden in Darjeeling, and describing it in a letter he sent to Kew in 1921, attached to a collection (Gamble 30867, K), he stated that 'it must have plenty of room as the rhizomes are long and send up shoots at intervals so that it does not form clumps'. Thorns were not mentioned at all.Therefore it would seem quite certain that Yushania is the appropriate genus for this species, although further fieldwork is still required to investigate all the bamboos found by Pantling's collectors on the Rechi La in Sikkim in September 1895.Unfortunately this locality is in a sensitive border area, and it is not likely that foreigners will be allowed to visit it.Arundinaria pantlingii is likely to flower there in A.D. 2005, having a well-documented flowering cycle of around 36 years.
Three other species now placed in Yushania were also initially described by Gamble (1896): A. hirsuta, A. microphylla, and A. rolloana.A further species, Arundinaria maling Gamble, was separated from Arundinaria racemosa Munro at a later date (Gamble, 1912).With the exception of A. maling these species were only briefly described and have remained largely unknown.The Chinese literature includes two further binomials based upon material from Tibet, Y. xizangensis Yi, and Y. yadongensis Yi (with which Y. longissima Yi nom.illeg. is synonymous).

SPECIES ENCOUNTERED IN NEPAL AND BHUTAN
Four species have been encountered so far in Nepal and Bhutan.Yushania hirsuta and Y. pantlingii are large, vigorous species that often form dense, impenetrable thickets, and can suppress tree regeneration if clear-felling removes the canopy completely.They are resilient bamboos with rhizomes that penetrate to considerable depth.They occupy ecologically similar habitats and survive in what are, for bamboos, relatively dry sites.They have few uses and can be categorized as pernicious weeds.Yushania rolloana (Gamble) Yi from Nagaland is very similar to Y. hirsuta, and may be synonymous, but its flowers are not known.
Yushania maling and Y. microphylla are species of smaller stature.Y. maling is a common component of the temperate forest understorey in eastern Nepal and southern Bhutan.In western Bhutan some plants have a ring of light hairs at the base of the culm sheath, smoother culms, thinner culm walls, proximal leaf sheaths with ciliate edges, and larger leaf sheath auricles.Y. microphylla is a similar species, but has hollow rhizomes, which may allow it to succeed on flatter and wetter sites than other Yushania species.It forms large areas of pastureland in central Bhutan as well as occurring in the forest understorey.It is often dwarfed by grazing to a low sward with very small leaves.The leaves of the type specimen were obviously taken from heavily grazed plants, and were unrepresentative of the species.The principal characteristics of Y. microphylla are its hollow rhizomes, the thickened transparent exterior leaf edge, and its smooth culms, with persistent wax below the nodes.The flowers are still not known.
The two Tibetan species were given detailed descriptions although the type specimens are infertile.Y. yadongensis seems very close to Y. microphylla, but the description does not mention the hollow rhizomes or thickened leaf margins, which are the principal characteristics of the latter species.It was described from material collected near Yatung in the Chumbi Valley between Sikkim and Bhutan.Y. xizangensis seems from its description to be close to Y. maling.It was collected in Tibet to the north of eastern Bhutan and in Arunachal Pradesh, and differs from Y. maling in having no leaf sheath auricles or oral setae.The species known from Nepal and Bhutan are keyed out below.

TABLE 1 .
Principal characteristics of the main temperate Sino-Himalayan genera with pachymorph rhizomes, including the new genus Borinda.
little or no fasciculation.Panicle branches subtended by very small remnants of sheaths or rings of hairs, with branch prophylls represented by the lower glumes of pedicellate spikelets.Mid-culm branch buds enclosed by single 2-keeled prophylls, always open at the front.Lateral branch axes always subtended by sheaths.Basal culm buds open.Leaf venation strongly tessellated.