Hydnora ­arabica (Aristolochiaceae), a new species from the Arabian Peninsula and a key to Hydnora

Abstract

The plant parasite Hydnora arabica (Aristolochiaceae) is described from the Arabian Peninsula. This species was previously identified as Hydnora africana in Oman. It can be separated from other Hydnora taxa primarily by its terete rhizome, red to orange inner perianth tube color, and tepal lobe margins entirely covered with dense strigose setae. In Oman, Hydnora arabica is known to parasitize two leguminous trees: Acacia tortilis and the introduced Pithocellobium dulce, but may parasitize additional Fabaceae. At least eleven synonyms or subspecific varieties of H. abyssinica are described in the literature, all from east or southern Africa. These synonyms are discussed in light of new observations of morphology including tepal margin ornamentation. A new key for Hydnora is proposed.

Hydnora: The strangest plant in the world?

“…Hydnora has a narrow host range, and is parasitic upon the roots of host plants in the spurge (Euphorbiaceae), legume (Fabaceae), and torchwood (Burseraceae) families (Bolin et al, ; Bolin et al, ; Musselman & Visser, ). Host specificity can act as a catalyst for speciation in parasitic plants, in which cryptic species can be overlooked because of their reduced morphological features (Thorogood, Rumsey, Harris, & Hiscock, ).…”

“…Because of their furtive life histories, poor representation in herbaria, and recalcitrance to cultivation, empirical data and controlled experiments to test the host specificity of Hydnora are lacking. However the existence of distinct Euphorbia ‐parasitizing, and Fabaceae and Burseraceae‐parasitizing lineages of Hydnora , respectively (Bolin et al, ), indicates that host specificity may have played a role in speciation.…”

“…This holoparasitic (non‐photosynthetic) plant, only emerges above ground to flower, can damage infrastructure by bursting through pavements (Maass & Musselman, ), and scarcely resembles any other flowering plant. Eight species of Hydnora are now recognized (Figure ), of which one ( H. visseri ) was identified in 2011 in a market, advertised as a traditional medicine, in Johannesburg (Bolin, Maass, & Musselman, ; Williams, Falcão, & Wojtasik, ), and another ( H. arabica ) was only described in 2018 (Bolin, Lupton, & Musselman, ). Their unpredictable and elusive flowering, together with their remote distributions, suggest more species await discovery.…”

Understanding the Ethnobotany, Chemistry, Pharmacology, and Distribution of Genus Hydnora (Aristolochiaceae)

“…Hydnoraceae is grouped under the Aristolochiaceae family and consists of parasitic plants characterized by large flowers and lacking leaves [ 1 , 2 ]. They are native and distributed in arid and semi-arid parts of Africa and Asia.…”

The First Plastid Genome of the Holoparasitic Genus Prosopanche (Hydnoraceae)

“…In contrast to all other parasitic angiosperm lineages Hydnoraceae are the only lineage outside the monocot and eudicot radiation and among one of the oldest parasitic lineages with an estimated stem group age of~91 MYA [29]. The family consists of the two genera Hydnora (7 species) [30] and Prosopanche (5/6 species) [31] with Hydnora occurring exclusively in the Old World and Prosopanche in the New World [32,33]. According to molecular dating analyses the two genera split from each other about 54 MYA [29].…”