Rhamphicarpa Fistulosa, a Widespread Facultative Hemi‐Parasitic
Total Page：16
File Type：pdf, Size：1020Kb
Rhamphicarpa fistulosa, a widespread facultative hemi-parasitic weed, threatening rice production in Africa J RODENBURG*, J J MORAWETZ† & L BASTIAANS‡ *East and Southern Africa, Africa Rice Center, Dar es Salaam, Tanzania, †Rancho Santa Ana Botanic Garden, Claremont, CA, USA, and ‡Crop and Weed Ecology Group, Centre for Crop Systems Analysis, Wageningen University, Wageningen, The Netherlands to moist free-draining uplands). Rhamphicarpa fistul- Summary osa is relatively independent and persistent because Rhamphicarpa fistulosa is a facultative hemi-parasitic of the presumably wide host range, the facultative plant of the Orobanchaceae family, adapted to wet nature of its parasitism and its prolific seed (esti- soils. Apart from tropical Australia, it is only found mated 100 000 seeds mÀ2 under moderate infestation in sub-Saharan Africa, where it is considered a minor levels). Finally, R. fistulosa causes severe yield losses weed in cereal crops such as rice. Due to this status, (average 60%) and high regional annual economic the species has received only sporadic attention. losses (estimated US $175 million), while effective Recent field observations and encounters with rice control options are scant and awareness of the spe- farmers in several African countries showed that cies among important R&D stakeholders is almost R. fistulosa is, however, a more serious and increas- absent. An integrated approach is advocated to assist ing production constraint than previously thought. the rice sector to reduce current R. fistulosa-inflicted Results from a systematic literature review and a glo- losses and to prevent further spread of the species bal herbarium study support this. The species has a into new areas. broad distribution over Africa (at least 35 countries Keywords: rice vampire weed, inland valley, rain-fed from Madagascar to Senegal and from Sudan to lowland, parasitic plant, integrated weed management, South Africa) and a wide range in altitude (0– subsistence farming, sub-Saharan Africa. 2150 m a.s.l.) and environment (waterlogged swamps and common feature in the natural vegetation of Introduction ephemeral wetlands (e.g. Hansen, 1975; Cisse et al., Rhamphicarpa fistulosa (Hochst.) Benth. (Orobancha- 1996; Deil, 2005; Muller€ & Deil, 2005; Muller,€ 2007), ceae) is an annual, facultative hemi-parasitic forb spe- as well as in agro-ecosystems of tropical Africa, includ- cies (Hansen, 1975; Ouedraogo et al., 1999). Although ing cropping systems characterised by dryer soils much less well known than other weedy members of (Ouedraogo et al., 1999; Gworgwor et al., 2001; Ro- Orobanchaceae, such as Striga Lour. spp., Orobanche denburg et al., 2011). The species is increasingly L. spp. and Phelipanche Pomel spp., it is a widespread encountered and perceived as a noxious weed in rice. Rice farmers and agricultural extension agents lack ber of local names in many of the countries where it knowledge on effective management strategies for this occurs as a weed in rice (see Table 1). Based on the species. This is mainly a result of the low awareness of species’ parasitic nature and the most common host its existence and consequently the low priority it has crop species, rice vampire weed is proposed as the so far received for research and development (Schut common name of R. fistulosa. et al., 2014). Indeed, many knowledge gaps exist with Plants are erect and slender, simple-stemmed and respect to R. fistulosa. There is an urgent need to (mostly) glabrous, with smooth needle-like pale green understand just how important the species is in terms leaves, in opposite arrangement (Fig. 1A and B), and of its distribution, invasiveness and agronomic and can reach up to 120 cm height, depending on locality economic impacts. Secondly, effective management (Philcox, 1990). The species is adapted to semi-aquatic strategies should be developed that prevent the species’ environments, with large (air) spaces between the corti- spread and reduce crop damage. Knowing the ecologi- cal cells of the root aerenchyma to facilitate air flow cal and biological characteristics of the plant is of under submerged conditions (Neumann et al., 1997; utmost importance for the development of such strate- Ouedraogo et al., 1999). gies. While researchers, mainly botanists, have studied Mature plants are branched and may turn reddish and reported on R. fistulosa since 1835, when it was (Fig. 1C). Flowers are white, cream, pale pink or pale first described and named, the information is scattered blue (the white form is most common in Africa) and far from complete. A structured and co-ordinated (Fig. 1D) with long tubes (25–30 mm) that are straight approach is advocated to complete the missing infor- or slightly curved (Hansen, 1975; Fig. 1A and D). The mation and increase our understanding of this species. fruits are asymmetrical and neatly beaked (Fig. 1A To this end, we have reviewed all publicly available and B), about the size of a small pea, that is 6–15 mm publications and herbarium specimens of this species. long and 4–7 mm broad, containing 100–250 dark The objectives were to provide an overview of the cur- brown seeds. Seeds are oval shaped, 0.2 9 0.55 mm, rent knowledge and understanding of the species’ dis- and the outer seed coat forms a reticulate network tribution, biology, ecology, invasiveness, agronomic covered by prominent ridges (Fig. 1A; e.g. Mielcarek, and economic importance and management and to 1996; Ouedraogo et al., 1999) and weigh about identify and prioritise research questions. The overall 0.011 mg (Rodenburg et al., 2011). For complete aim of this review was to alert decision and policy botanical descriptions, see Hansen (1975) and Ouedra- makers and stakeholders of the emerging problem ogo et al. (1999). caused by R. fistulosa and to prioritise and guide Bentham (1835) was the first to describe a species research and development efforts aimed (i) at the con- within this genus, that is Rhamphicarpa longiflora trol of this species where it has already turned into a Benth. Independently from this work, Hochstetter weed and (ii) at the prevention of spread into new (1841) named the genus Macrosiphon and described areas. two African species, M. fistulosus Hochst. and M. elongatus Hochst. These are currently considered synonyms of Rhamphicarpa fistulosa and R. elongata What do we know about the plant species (Hochst.) O.J. Hansen respectively (Hansen, 1975). In R. fistulosa? total, 41 different names of species and subspecies (or varieties) have been given to plants presumed to Taxonomy, nomenclature and similarities to other species belong to Rhamphicarpa, but many of them are no longer accepted. For instance, Hooker (1884) and van Rhamphicarpa fistulosa is an angiosperm species of the Steenis (1970) considered the African, Australian and Lamiales order, Orobanchaceae family (formerly Indian species to be different. The Australian plants Scrophulariaceae; Olmstead et al., 2001) and the genus were named R. australiensis Steen., but as van Steenis Rhamphicarpa (Bentham, 1835; Hochstetter, 1841; Ben- did not compare this species to the African or Cauca- tham, 1846; Engler, 1895; Hansen, 1975; Philcox, 1990; sian species, this name was not widely acknowledged. Mielcarek, 1996; Fischer, 2004; Table 1). Its phyloge- In the literature prior to Staner’s (1938) revision, many netic position is not yet completely confirmed, but the species that are currently considered to be part of the species R. fistulosa has been placed under the tropical genus Cycnium were classified as Rhamphicarpa; For clade of Orobanchaceae previously reported by Mora- example, the hemi-parasitic Cycnium veronicifolium wetz et al. (2010), with Fischer et al. (2012) showing (Vatke) Engl. used to be called Rhamphicarpa veronici- its closest relatives being the genera Sieversandreas Eb. folia Vatke (Fuggles-Couchman, 1935; Parker & Fisch., Bardotia Eb. Fisch. Schaferh.€ & Kai Mull.€ and Riches, 1993). The closely related genera Rhamphicarpa Randamaea Benth. The species R. fistulosa has a num- and Cycnium are distinguished based on the form of Table 1 Taxonomy, scientific, common and local names of Rhamphicarpa fistulosa Scientific name Rhamphicarpa fistulosa Authors Hochstetter (1841), Bentham (1835, 1846), Engler (1895) Common name Rice vampire weed Family Orobanchaceae (formerly: Scrophulariaceae) Tribe Buchnereae (formerly Gerardieae) Order Lamiales Class Angiospermae – Dicotyledons Synonyms Macrosiphon elongatus Hochst. Rhamphicarpa longiflora (Indian species most related to R. fistulosa) Benth. Macrosiphon fistulosus (synonym of R. longiflora) Hochst. Rhamphicarpa australiensis Steenis Vernacular Tutari (R. longiflora) – India – Maharashtra state (Marathi) names Grassland trumpet or trumpet flower – India (English) (R. longiflora) Kayongo – Uganda – Namutumba District (Lusoga) Otcha, Do, Corico, Efri – Benin – Dassa, Glazoue Districts (Idaatcha) Mbosyo – Tanzania – Kyela District (Nyakusa) Ntengo ya nchele nchele – Tanzania – Mbinga District (Nyasa) Mulungi – Tanzania – Ifakara (Kisajala) Angamay – Madagascar – Mid West (Malagasy) Mogogatau – Zambia – North (Tswana) Loho Soukoh/Soukoh lo^ – Cote d’Ivoire – North: Korhogo/Boundiali (Dioula/ Senoufo) Sources: Hochstetter (1841), Bentham (1835, 1846), Engler (1895), von Wettstein (1891), Steenis (1970), Hansen (1975), Ouedraogo et al. (1999), l’Herbier de Parc Botanique et Zoologique de Tsimbazaza, Antananarivo, Madagascar, Herbarium of the Department of Bot- any, University of Dar es Salaam, Museum National d’Histoire Naturelle, Paris, France (SONNERAT). the