Paspalum sanguinale (Linn.) Lam. var. rottleri Hook.f. is typified by two sheets, Wight 3032 and Wight 3033, both at Kew. Of these, the former is Digitaria ciliaris and the latter Digitaria bicornis (Lam.) Loud. In the protologue to the variety, Hooker described the wings of the rhachis as being “two or three times broader than the midrib.” Since this character does not agree with Digitaria bicornis (including Wight 3033), the specimen Wight 3032 is selected as the lectotype of var. rottleri. This is included in the synomymy of Digitaria ciliaris because the spikelets are narrow and apparently lack the spiny protuberences on the nerves of the lemma.
Digitaria ciliaris is a polymorphic species showing at least four parallel series based on quite independent sources of variation. The rhachis may have long white hairs (rhachiseta) or not; in terms of indumentum the spikelets of a pair may be the same or different (biformis); the spikelets (independently in each pair) may be glabrous (nubica), long or short hairy (ciliaris, desvauxii) or conspicuously fringed (criniformis, fimbriata); one or both spikelets may be beset with stiff glassy bristles (chrysoblephara, willdenowii). None of these variants shows any indication of geographical segration, and since there are at least these four independent sources of variation the number of potential varieties is enormous, but none would be of any taxonomic significance. The sporadic occurence of the siliceous spines characteristic of Digitaria sanguinalis in spikelets otherwise typical of Digitaria ciliaris suggests that there may be some gene-flow between these two species in Pakistan.
Digitaria bicornis (Lam.) Loud. is often included in subsp. chrysoblephara (or vice versa, see Veldkamp 1973) by virtue of its possession of glassy bristles, but like Digitaria ciliaris it too shows several types of indumentum and quite frequently is perfectly glabrous (even to the exclusion of the glassy bristles). It is in fact a distinct species differing in a number of important characters. There are normally only 2, sometimes 3 racemes each with a slightly swollen base. The midrib is thick and the wings are usually extremely narrow. The pedicels are stout and straight and this, combined with the thick midrib, gives the spikelets the appearance of being sunk in the rhachis. The lower lemma is horny with much thickened, contiguous or closely spaced nerves. The first pair of interspaces, and the second where present, are reduced to deep V-shaped grooves. The lemma characters are best seen in the subsessile spikelets towards the base of the raceme. True Digitaria bicornis does not occur in Pakistan, being confined to the warmer parts of southern India, Sri Lanka and Burma.
Syntype for Panicum adscendens Kunth Catalog Number: US 102021 Collection: Smithsonian Institution, National Museum of Natural History, Department of Botany Verification Degree: Original publication and alleged type specimen examined Preparation: Pressed specimen Collector(s): F. W. Humboldt Locality: Mexico, Central America
Syntype: Kunth, C. S. 1816. Nova Genera Sp. Pl. 1: 97.
Digitaria ciliaris is a pantropical, weedy annual very variable in spikelet pubescence and nervation. It lies at the center of a complex of similar and somewhat intergrading, weedy species including D. bi-cornis, D. cruciata, D. henryi, D. radicosa, D. sanguinalis, and D. seti-gera. Occasionally intermediate specimens will be encountered that are difficult to place.
Most species in this complex include forms with or without stiff, glassy bristles near the margins of the lower lemma. These lie flat along the lemma when young, coloring yellow and spreading as a conspicuous pectinate fringe at maturity. The pectinate form of Digitaria ciliaris is sometimes distinguished at varietal rank.
Syntype for Syntherisma sericea Honda Catalog Number: US 2947407 Collection: Smithsonian Institution, National Museum of Natural History, Department of Botany Verification Degree: Card file verified by examination of alleged type specimen Preparation: Pressed specimen Collector(s): B. Hayata Year Collected: 1919 Locality: Fukibi., Taiwan [Formosa], Taiwan, Asia-Temperate
Syntype: Honda, M. 1924. Bot. Mag. (Tokyo). 38: 127.