We reviewed the names used for Cistanche in Iraq and neighbouring countries. The sources that were used to identify species of Cistanche putatively in Iraq, and the species in their accounts, were as follows:

1. Flora of Lowland Iraq (Rechinger 1964a). Rechinger’s account referred to two species, C. tubulosa (Schenk) Wight ex Hook.f. and C. salsa (C.A.Mey.) Beck. He presented a key discriminating the species by height, pubescence and anther cell shape. C. tubulosa was described as a larger plant, 60–100cm, glabrous, and with obtuse anther cells. C. salsa was reported to grow up to 40 cm, lanate to glabrescent, and with acuminate anther cells. Five specimens of C. tubulosa and one of C. salsa were examined.
2. Flora Iranica (Rechinger 1964b), in which Iran, Persia, Afghanistan, parts of West-Pakistan, Iraqi Kurdistan, Azerbaijan and Turkmenistan listed C. ridgewayana Aitch. & Hemsl., C. fissa C.A.Mey.) Beck, C. salsa, C. eremodoxa Bornm., C. laxiflora Aitch. & Hemsl., C. tubulosa and C. flava (C.A.Mey.) Korsh. There were no reports of Cistanche species in autonomous Iraqi Kurdistan.
3. The Flowering Parasitic Plants of Iraq (Karim 1978) cites only C. tubulosa. Karim (1978) was aware of seven plants and cited three host species.
4. In an unpublished PhD thesis that included a monographic treatment of genus Cistanche, Ataei (2017) cited two species in the exsiccatae for Iraqi specimens: C. tubulosa and C. flava. She referred to the C. salsa specimen cited by Rechinger (1964a), considering it to be a misidentified specimen of C. ambigua (Bunge) Beck. In the treatment she also referred to an, as yet, unpublished species found in Iraq, but no specimen from Iraq was cited.
5. In an unpublished thesis entitled taxonomical and ecological study of parasitic plants of Iraq, Al-Asady (2017) cited only one species, C. tubulosa to occur in Iraq. The C. salsa specimen of in the Flora of Lowland Iraq (Rechinger 1964a) was considered to be a misidentified specimen of C. tubulosa.
6. The Ecology and flora of Basrah (Al-Mayah et al. 2016) cites only C. tubulosa. Al-Mayah et al. (2016) refer to ‘Zib AL-Zumal’, ‘Thenun AL-Jinn’ and ‘Halook’ as common names for C. tubulosa in Iraq. They also cite Haloxylon salicornicum (Moq.) Bunge ex Boiss. (Amaranthaceae) and Zygophyllum propinquum Decne. (Zygophyllaceae) as host species.
7. In their book on parasitic plants, Al-Mayah and Al-Asady (2022) stated only C. tubulosa to occur in Iraq. They cite the following hosts: Haloxylon salicornicum (listed under its synonym: Hammada salicornica (Moq.) Iljin) (Amaranthaceae), Zygophyllum propinquum (listed under its synonym: Tetraena propinqua) (Zygophyllaceae) and Capparis spinosa L. (Capparaceae).

1. The Flora of Syria, Palestine and Sinai (Post 1932) covers the region from the eastern Mediterranean seaboard to the Syrian Desert. This flora recorded C. lutea (Desf.) Hoffmanns. & Link, C. tubulosa and C. salsa. In the descriptions, C. lutea and C. tubulosa are described as glabrous and C. salsa as lanate. Of the three species, only C. lutea is reported to occur in the desertic regions contiguous with Iraq.
2. In the Flora of Turkey (Davis 1982), C. salsa is the only species recorded. It is described as having densely lanate bracts and bracteoles, and a glabrous calyx and corolla. It was cited in three regions, two were in Inner Anatolia and one was in Kars city which is only 370 km from the Iraqi Kurdistan border. Therefore, C. salsa is a possible candidate species for the Flora of Iraq.
3. The Flora of Saudi Arabia (Migahid 1989) recorded two species, C. phelypaea (L.) Cout. (generally considered an Atlantic species) and C. tubulosa. Other species that are not included in the Flora have not been recorded for Saudi Arabia. These are C. violacea and C. rosea Baker (Foley 2004). The distribution of these species is narrow, C. rosea is distributed in the far south west and C. violacea in the northwest, far from the border with Iraq.
4. The Flora of Kuwait (Daoud 1985) records only C. tubulosa, cites Soda rosmarinus (Bunge ex Boiss.) Akhani (listed under its synonym: Seidlitzia rosmarinus Bunge ex Boiss. (Amaranthaceae) as a host, and considers C. tubulosa var. tomentosa Hook.f.i.c as a Synonym.

Protologues for Cistanche eremodoxa, C. salsa, C. ridgewayana, C. fissa, C. laxiflora, C. flava, C. ambigua, C. lutea and C. phelypaea — the species identified as putatively in Iraq and adjacent regions of neighbouring countries — were examined as well the description of the unpublished putative species C. chabaharensis (Ataei 2017). Type specimens of these species were examined when they were available; type specimens of C. flava and C. tubulosa were unavailable, and are believed to be missing. The Natural History Museum, London (NHM) and the University of Vienna (WU) collections were examined, but they held no Iraqi specimens. An extensive survey of three herbaria: Kew (K), Edinburgh (E) and the Natural History Museum of Vienna (W) and examination of herbarium images from the National Herbarium in Baghdad (BAG) retrieved 62 specimens from Iraq. Specimens from adjacent countries were also examined for comparison. Images of living material in Iraq and adjacent countries sourced from social media were all examined, and cross-referenced with herbarium specimens.

Google Earth was used to create coordinate assumptions for those specimens for which true coordinates were unavailable (Fig. 1). Coordinates were exported to QGIS 3.4 with layers from the Natural Earth Quick Start Kit. Host species were recorded from specimen labels or based on identifications of host plant material mounted on the same sheet as the specimen. In the absence of excavation of host-parasite connections, the identity of the host was considered tentative (the parasite can appear some distance above ground from the host plant).

Figure 1. 

The locations of the material examined in Iraq.

A literature review of Iraq and of adjacent countries, and of other relevant taxonomic studies, identified 10 published names and one unpublished name for species putatively in Iraq and adjacent countries. Species in adjacent countries, especially in Iran including, C. eremodoxa, C. ridgewayana, C. fissa, C. laxiflora and C. ambigua, were excluded from this investigation as their distributions and morphology suggest they are unlikely to exist in Iraq. Of the other species, two Atlantic/western European taxa were excluded on the basis that they are exceptionally unlikely to occur in the Middle East: C. lutea and C. phelypaea. Although C. lutea was cited in the Flora of Syria, Palestine and Sinai, the description does not provide adequate detail of morphological characters to discriminate between this and other species, including C. tubulosa. Cistanche phelypaea, as circumscribed currently, is a primarily Atlantic, coastal species, frequent from southwest Portugal south to Macaronesia and the coast of Morocco. We consider the inclusion of C. phelypaea in the Flora of Saudi Arabia to be equivocal, and cited with insufficient detail to merit further examination. Moreno Moral et al. (2017) consider C. lutea and C. phelypaea to be morphologically distinct. Wood (1997) records the presence of C. phelypaea and C. rosea Bakir in Yemen and considered C. tubulosa a synonym of C. phelypaea. Author AM during his time in Yemen at the University of Taiz, in 2000–2002, observed a putatively distinct form of Cistanche across regions. It parasitized Halothamnus bottae Jaub. & Spach (syn. Salsola bottae (Jaub. & Spach) Boiss) (Amaranthaceae) (absent from Iraq) and was pure yellow, without purple pigmentation. Further investigation is required. Cistanche rosea, which is widespread across the Arabian Peninsula, is readily distinguished by its deep rose-red corolla. Ataei et al. (2020) asserts that C. lutea and C. phelypaea do not occur in the Middle East. Both entities were excluded from further work for the treatment of the genus Cistanche in Iraq.

Finally, we considered C. chabaharensis, an as yet unpublished name referred to in the thesis of Ataei (2017) (Fig. 2B). This description placed focus on the glabrous, acute anthers; the key also described bract and bracteoles to possess non-sinuate margins, yellow corolla, and anther filaments glabrous at the base. However, on close examination of specimens cited by Ataei (2017) from Oman (McLeish, E00121976 E) and Iraq (Barkley & Abbas-Al-Ani, 6499 K), it was apparent both had woolly anthers that could not be distinguished from anthers of C. tubulosa, and that the bracts and bracteoles were sinuate. We consider it doubtful that this unpublished name represents a new entity found in Iraq; rather we believe this to be an entity that falls within the bounds of variability in C. tubulosa s.l. In summary, only three species warranted detailed investigation for the region in question: C. tubulosa, C. salsa and C. flava (Table 1; Fig. 3).

Figure 2. 

A herbarium specimen of C. tubulosa collected in Iraq, mistakenly identified as C. flava B the holotype of putative species C. chabaharensis; note the woolly anther (inset) typical of C. tubulosa C herbarium specimen of C. tubulosa in (W) collected in lowland of Iraq, mistakenly identified as C. salsa.

Figure 3. 

Illustrations of Cistanche species putatively found in Iraq and adjacent territories (inflorescences) A C. flava B C. tubulosa C C. salsa D–F corollas in profile of C. flava, C. tubulosa and C. salsa, respectively; note calyx and bract characteristics.

Here we consider the three taxa identified to potentially co-occur in the region. Cistanche salsa can be readily differentiated from C. flava and C. tubulosa by its hairiness; the latter two species are glabrous (see key). Cistanche flava is differentiated from C. tubulosa by its scarious, conspicuously long bracts which are twice as long as the calyx or even longer (Table 1; Figs 3A, D, 4C, D). Sánchez Pedraja et al. (2016) consider C. flava to be a synonym of C. tubulosa, however the distinct bract morphology is apparent both in living and dried material. Detailed, well-sampled investigations of both taxa are absent, and their distinction remains open to question; however recent molecular work provisionally supports their separation (Ataei et al. 2020).

Figure 4. 

Cistanche species putatively found in Iraq and adjacent territories A, B C. tubulosa (photographed in Iran) C, D C. flava (photographed in Kazakhstan) E, F C. tubulosa (photographed in Iraq; note excavated stem bases in E). Used with permission: photographs A, B by Sajad Alipour; photograph C by Lina Valdschmit; photograph D by Bobur Karimov.

The name Cistanche tubulosa s.l. is used from Africa and the Middle East to South and Central Asia and China, however as currently applied, the name refers to a widely distributed, polyphyletic group of plants (Aldughayman et al. 2024). In the most complete phylogeny (Ataei et al. 2020), specimens identified as C. tubulosa (or aff. C. tubulosa) were placed in a ‘widespread clade’, but four specimens identified as aff. C. tubulosa were nested in a separate clade sister to C. flava, along with other plants identified as C. senegalensis (an entity considered by Beck-Mannagetta to be closely related to C. tubulosa, but differentiated on the basis of subequal lower corolla lobes, oblong bracts and the absence of purple pigmentation). Additionally, two specimens identified as C. tubulosa are in a subclade which otherwise includes the Central Asian species, C. laxiflora. The type specimen of C. tubulosa is lost, and the correct application of the name C. tubulosa is yet to be clarified although it does seem to be misapplied to specimens in the C. laxiflora clade (Ataei et al. 2020; Aldughayman et al. 2024). Recently, a specimen collected from South Sinai near the type locality was designated a neotype (Aldughayman et al. 2024). This neotypification, alongside further phylogenetic work, is necessary to re-evaluate whether the name Cistanche tubulosa is a synonym for the name C. tinctoria, as has been proposed by Moreno Moral et al. (2017), and also to confirm whether the name C. tubulosa is the correct name for any Iraqi entity. To avoid compounding confusion, here we use the name C. tubulosa, consistent with most authors, until this re-evaluation is completed.

All material we examined from four Governorates: Karbala, Basrah, Muthanna and Wasit correspond to C. tubulosa (in its current, most widely-accepted circumscription). None of the material we examined pertained to either C. salsa or C. flava, based on our careful consideration of the traits emphasized above. Similarly, none of the specimens tentatively labelled C. salsa corresponded with that species either (Fig. 2C); indeed, we only found evidence of glabrous plants, ruling out the occurrence of C. salsa in Iraq based on the material available. Furthermore, material from Iraq identified as C. flava in a doctoral thesis (Ataei 2017) appears to have been identified in error (Fig. 2A): the unbroken bracts do not greatly exceed the calyx; we believe detached bracts may have caused confusion; phylogenetic analysis later confirmed the specimen in question nested with C. tubulosa (Ataei et al. 2020).

Our extensive investigation based on herbarium specimens revealed that C. tubulosa occurs in every Governorate of Iraq except for the Kurdistan Autonomous Region. This could be due to the wide distribution of potential hosts across three of four main ecological regions, namely the deserts west of the Euphrates River, Upper Mesopotamia and Lower Mesopotamia (Ghazanfar and McDaniel 2016; Hegazy and Doust 2016). Cistanche has not been recorded in the fourth ecological region, the northern highlands of Iraqi Kurdistan. This region is an extension of the great Eurasian alpine system, and not a typical habitat for Cistanche which is primarily desert-dwelling; moreover, hosts typically associated with Cistanche – shrubby Amaranthaceae such as Haloxylon, are absent from this ecological region (Ghazanfar and McDaniel 2016; Hegazy and Doust 2016). We conclude from this examination that despite multiple reports of various taxa, only one species occurs in Iraq with certainty: Cistanche tubulosa.

It is of note that the corolla colour of C. tubulosa varies with age and population, from pale lemon yellow, to deep orange-yellow, with varying levels of pink to violet pigmentation. Similarly, the height and stature vary from 15 cm to 130 cm depending on rainfall and, potentially, host species. The key below is based on our observations of multiple populations across the region.

The authors have declared that no competing interests exist.

No ethical statement was reported.

No funding was reported.

Majed Aldughayman conducted the research, Chris Thorogood and Julie Hawkins wrote the manuscript; Abdulridha A. A Al-Mayah contributed to the work.

Chris J. Thorogood https://orcid.org/0000-0002-2822-0182

Julie A. Hawkins https://orcid.org/0000-0002-9048-8016

All of the data that support the findings of this study are available in the main text.