Dichanthium foulkesii

Landge, Shahid Nawaz & Shinde, Rajendra D., 2021, Synopsis of the genus Bothriochloa (Poaceae: Andropogoneae) in India, Phytotaxa 516 (1), pp. 43-58 : 56

Dichanthium foulkesii (Hook f.) S. K. Jain & Deshpande

In this species the pedicel is with an opaque median groove not as distinctly translucent as in typical Bothriochloa . This species with opaque pedicel and rhachis internode somehow links the members of Dichanthium with grooved pedicel to Bothriochloa species having a typical translucent pedicel and rhachis internode. This is mere a possible presumption which may only be ascertained with molecular support. The lower glume in this species is glabrous, spikelets efoveolate and leaves mainly cauline, differing from the close species B. pertusa primarily in efoveolate spikelets (vs. 1–2 pits on lower glume) and glabrous lower glume of fertile spikelet (vs. hairy below the middle, very rarely glabrous) and pedicelled spikelet narrower and longer than the sessile counterpart (vs. pedicelled spikelets almost equal to sessile spikelets).The former species has been treated under Dichanthium by Jain & Deshpande (1979). This species is slender, up to 90 cm high, nodes glabrous, leaves usually convolute and lower glume of sessile spikelet glabrous and often longitudinally depressed on the dorsal side. According to Hooker & Stapf (1896), A. foulkesii differs from B. ischaemum in much shorter hairs of the joint and pedicel (it has been annotated by Hooker on the type specimen sheet at K collected from Pykora [Pykara: a village in Tamil Nadu] by King in 1878). The awn in latter is 1.5 cm long (vs. awn up to 2 cm long in former) and lower glumes in both the species are equally 9 nerved.

Distribution: — Nilgiris (Tamil Nadu), Kerala & Karnataka (Mandya & Mysore) (Lakshminarsimhan et al. 2019). It is endemic to South India.

Dichanthium concanense (Hook f.) Jain & Deshpande and Dichanthium jainii (Deshpande & Hemadri) Deshpande

Dichanthium concanense and D. jainii , both the species have pedicels completely solid or slightly sulcate, spikelets efoveolate and leaves cauline. Therefore, they can be treated better under the genus Dichanthium than in Bothriochloa . The latter is so far only known from Maharashtra, which weakly differs from the former on the account of the characters, such as: racemes 3–15 (vs. 5–8 racemes), longer sessile spikelets 4.5–6.25 mm long (vs. 3.0–4.0 mm long), longer pedicelled spikelet 5.5–9.0 mm long (vs. 4.0–5.0 mm long), longer leaves 30 × 0.8 cm (vs. ca. 70 × 1.5 cm), and lower glume of pedicelled spikelet 15–19 nerved (vs. ±9 nerved) ( Deshpande & Hemadri 1971). We observed that in the former species raceme bases are quite slender and long, much in similar with Capillipedium . Interestingly, both of these taxa are endemic to Peninsular India. In Sedgwick’s collections (Sedgwick 4652: four sheets at BLAT) of D. concanense from Lingmala Fall, Mahabaleshwar (Maharashtra state), India the number of racemes in the panicle are up to 12 and ca. 9.0 cm long, 2–3 racemes in whorl from the swollen bearded node on 4.5 (–5.0) cm long rhachis, raceme bases long, ca. 1.5 cm long, ligule 3 mm long membranous-ciliate with fringed minute hairs and the sessile spikelets 4.8–5.0 mm long. These characters, discussed above, were considered by Deshpande & Hemadri (1971) taxonomically significant for B. jainii . In our study we found that these are still within the variable range of D. concanense . Were it not for the longer pedicelled spikelets and higher number of nerves on its lower glume, D. jainii would have been considered conspecific to D. concanense . A clear study is apparently in need.

However, Bor, who seemed to have examined the type specimens of the latter at K, said “This is one of those aberrant species of Bothriochloa , probably B. concanense ; though the spikelets are somewhat larger”. It is not unusual to find intermediates between these two species across varying ecological amplitude in the Western Ghats of Maharashtra. We have seen B. concanense growing through rocky crevices in shade in Matheran and on the flanks of the streams in the forest of Birmani , Mahabaleshwar , Maharashtra. The spikelets in this species appear to be little more of coriaceous, vernicose and tough nature than other congeners. Lower glume of sessile spikelet is distinctively longitudinally depressed in the middle .

According to Blatter in Blatter & McCann (1935), Dichanthium concanense “grows in large tufts in water-courses on rocks and sandy banks. The tufts look grayish owing to a waxy substance covering the plant all over, but easily removable”. We have seen this feature is quite useful at the identification of plants even in vegetative states. This grass is mostly associated with water bodies in Northern-Western Ghats of Maharashtra.

We discovered a small population of an unusually similar-looking grass to D. jainii at Gandikota Fort Hill, Andhra Pradesh (the herbarium specimen is at BLAT “ Shahid Nawaz GK-312”) in which the leaf blades are considerably shorter, rigid, pilose, glaucous and conduplicate, racemes only three, spikelets much narrower (ca. 1.0 mm wide), giving it a unique appearance but it may be tentatively placed between D. concanense and D. jainii . A facie of such a sort might have been influenced by the effect of drier habitats far removed from the wet Western Ghats of Maharashtra where D. jainii is believed to be endemic. In our specimen the pedicel and rhachis internode are distinctly terete and thickened upwards unlike slender and compressed — as typical of Dichanthium and Bothriochloa . Yet, we have not come to a fine conclusion about this species, into which considerable attention shall soon be given.