Pennisetum Rich.

Veldkamp, J. F., 2014, A revision of Cenchrus incl. Pennisetum (Gramineae) in Malesia with some general nomenclatural notes, Blumea 59 (1), pp. 59-75 : 63

Pennisetum Rich.

The genus was described by Richard (1805). The name refers to the often feathery bristles surrounding the spikelet(s). He included five species of which P. typhoideum Rich. was designated as the lectotype by Hitchcock (1920: 245). However, as Richard cited Holcus spicatus L. (1759: 1305) and an illustration by Plukenet (1691) these make it a superfluous name, and here it is placed under Cenchrus americanus (L.) Morrone. See below.

Pennisetum cenchroides Rich. , based on C. ciliaris L. (1771: 302), is also a superfluous name as ‘ ciliare ’ should have been used. This was done by Link (1827). It shows an early observa- tion that Cenchrus and Pennisetum are similar.

Pennisetum glaucum (L.) R.Br., Pearl millet, probably derived from P. violaceum (Lam.) Rich. , was cultivated in W Africa (e.g. northern Mali) 4 500 years ago and ‘soon’ after, at least 4 000 years ago, was present in India. Other species world wide are of importance as soil binders ( P. clandestinum Hochst. ex Chiov. , P. orientale Rich. ), forage (e.g. P. orientale, Oriental fountain grass, P. pedicellatum Trin., Barra grass, P. purpureum Schumach., Elephant grass, but inedible to cattle when mature, cur- rently used as biofuel), weeds (e.g. P. polystachion (L.) Schult., see below), and ornamentals (e.g. P. advena Wipff & Veldk. , P. alopecuroides (L.) Spreng., P. macrostachys (Brongn.) Trin. , P. orientale , P. setaceum (Forssk.) Chiov. (as P. ruppellii Steud. ), P. villosum R.Br. ex Fresen. , P. violaceum (Lam.) Rich. , etc.). Under Pennisetum orientale Richard cited in synonymy Cenchrus orientalis Willd. , which is an unpublished name that has also been mentioned as Willd. ex Kunth (1833: 162). There it was also in the synonymy of P. orientale , and so it is an invalid name, and only recently was validated by Morrone (2010: 128). Morrone noted that the type was not located, but it is a collection by Abbé [Dominique] Sestini (1750–1832) in the Willdenow Herbarium (BW- 1477) from Galathia (C Asian Turkey).

Pennisetum setosum (Sw.) Rich. is based on C. setosus Sw. (1797: 211) , but there reference is made to Swartz (1788: 26). Panicum polystachion Murray (1784: 105) is cited in such a way that it resembles a synonym, but in a commentary Swartz said “a Panico polystachyo L. minime diversum”. Brunken (1979) and Schmelzer (1997: 63) have suggested that the annual dip- loid ( ‘ polystachion ’) and perennial polyploid plants ( ‘ setosum ’) represent two subspecies or species.As the bases of the plants are rarely collected, and the chromosome number is of course not known, it is usually impossible to say what is what.

As said, Pennisetum typhoideum Rich. was based on Holcus spicatus L. (1759) and Gramen alopecuroides spica maxima Indiae orientalis Pluk. (1691: t. 32, f. 4) ( Fig. 2 ), which Plukenet later (1696: 174) renamed to Gramen paniceum s. Panicum sylvestre maximum indiae orientalis , names that have not been accounted for by Trinius (1822). Richard’s citations make P. typhoideum a superfluous name.

This illustration was also cited by Linnaeus who provided a different phrase name again.

However, in LINN there is 1212.1 which Linnaeus tried to identify with existing literature. I would think that this would be the lectotype of H. spicatus , but the combination has been lectotypified with Plukenet (1691: t. 32, f. 4) by Davidse (1994: 363). I feel that according to Art. 9.12 (ICN; McNeill et al. 2012) this uncited specimen should have preference and I here designate it as the lectotype.

Under Alopecurus typhoides Burm.f. (1768: 27) also cited Plukenet, uniting the plate (1691) with the text (1696: 174). Because both the Richard and the earlier Burman combinations are based on the same pre-Linnaean reference, even when Richard did not cite Burman, the latter is to be regarded as the author of the basionym to be cited within parentheses (Art. 41.4, Ex. 7), and the epithet is then to be spelled accord- ingly as ‘ typhoides ’.

Pennisetum violaceum (Lam.) Rich. was based on Panicum violaceum Lam. (1791: 169) from Senegal. The type is Rousillon s.n. (? holo P-LAM). The species is used as an ornamental and in hybridization experiments as it is regarded as the progenitor of P. glaucum (= Cenchrus americanus ).

Figures

Fig. 2 Gramen americanum spica echinata majoribus locustis Plukenet, Phytographia 1: 174, t. 92, f. 3. 1691.