Cistanche laxiflora Aitch. & Hemsl.

Ben-Natan, Dar & Thorogood, Chris, 2025, A revision of the genus Cistanche (Orobanchaceae) in Israel, and considerations for its taxonomic circumscription in the Middle East, PhytoKeys 260, pp. 213-236 : 213-236

Cistanche laxiflora Aitch. & Hemsl.

Description.

A holoparasitic (achlorophyllous), glabrous herb, with a stout stem, swollen at the base. Plant robust, 30–120 cm, with white or pale grey to pale lilac stem, 20–40 mm in diameter. Lower scales dense, constricted, entire, wide-triangular, yellowish, 10 × 10 mm. Middle and upper scales and floral bracts triangular-lanceolate, fleshy, entire, non-scarious and non-serrate, or sometimes very slightly serrulate, white or grey to pale lilac, 10 × 25 mm. Inflorescence a more or less lax spike with 40–200 flowers, 30–100 cm long, 5–8 cm in diameter, with or without a stem up to 20 cm below. Flowers at the base of the inflorescence sometimes with pedicels up to 15 mm long. Floral bracts about as long as calyx, or somewhat longer. Floral bracteoles 2, linear, obtuse, 2–4 × 10–15 mm, white, pale grey or pale lilac, fleshy, sometimes slightly serrulate at the margin, entire, non-scarious, attached to the calyx base and slightly shorter than calyx. Calyx tubular-campanulate, 13–17 mm. Calyx lobes 5, equal to subequal, oblong-rounded, entire, slightly scarious along the margins. The apical lobe 3–5 × 8–12, usually slightly shorter than the rest (3–5 × 11–15), sometimes the two bottom lobes slightly shorter than the side lobes (by 1 mm at most). Corolla infundibuliform, pentamerous, 30–35 mm. Corolla tube white, sometimes tinged lilac externally, with two yellow, flat, inconspicuous folds inside. Corolla tube arched at the middle or just beneath. Tube 15–16 mm below the arch, and 15–20 mm above. Inner tube more or less very short-pubescent around the filament bases, glabrous elsewhere. Limb whitish to very pale mauve or violet, 20–25 mm in diameter. Corolla lobes 5, rounded, equal or the upper ones slightly smaller than the other 3, usually wider than long. Stamens 4, inserted at about 1 / 3 the total corolla length, included. Filaments 15–20 mm, more or less short-pubescent at the base, glabrous or very sparsely, very short-glandular elsewhere. Anthers 3–4 × 2 mm, sparsely lanuginose, apically rounded, usually with a small tubercule at the base. Stigma lobes white. Ovary tubular-elliptic, white or yellowish-white with a yellow ring at base, dark brown when dry, 10–15 × 5–8 mm. Capsules ovoid-globose, 13–25 × 5–15 mm, dehiscent with 2–4 valves. Fl. March-April.

Habitat and prevalence.

Sandy-loessial soils and alluvial gravel near springs or over high-level ground water in the desert. This species is extremely rare in the region, currently known from 4 localities and threatened by depleting levels of ground water.

Host.

Probably Tamarix nilotica (Erenb.) Bunge, 1852 ( Tamaricaceae ), which we observed in association with the parasite in all four localities.

Notes.

All four populations co-occur with C. tubulosa . The two distinct species co-occur in sympatry and although they bloom simultaneously, intermediate morphotypes have not been observed – although molecular data shows there are rare events of hybridization (Ein-Gidron).

Specimens examined.

Israel • Arava Valley, Ein Hosb (En-Hatzeva) , 9. April. 1950. Near spring, on roots of Tamarix maris-mortui Gutmann, Zohary D. ( HUJ 123665 !) ; Israel • Negev desert, Makhtesh Ramon, Ein-Saharonim , coor. 30°36'06"N, 34°56'17.2"E, 300 m, Wet, somewhat saline sandy banks of a small freshwater stream, 14 April 2020. Dar Ben-Natan and Mimi Ron ( HUJ 133363 !, HUJI 133366 !, HUJ 133364 !, HUJ 133361 !, HUJ 133365 !, HUJ 133369 !, TELA 2050 !, TELA 2051 !) ; Israel • N. Arava Valley, Lower Ein Gidron, N. of Hatzeva , sand and grit, near flowing water, coor. 30°47'46.9"N, 35°16'34.4"E, 190 m, 22. April. 2021. parasitic on T. nilotica (Ehrenb.) Bunge ? together with Imperata cylindrica (L.) Raeusch. Dar Ben-Natan and Mimi Ron ( HUJ 133398 !) ; Israel • N. Arava Valley, Lower Ein Gidron . Dry capsules with 4 valves. 6. Oct. 2021. Dar Ben-Natan and Mimi Ron ( HUJ 134741 !) ; Israel • E Negev, Ein-Akrabim , coor: 30°53'34.8"N, 35°09'13.9"E. Parasitic on T. nilotica (Ehrenb.) Bunge. 26. Mar. 2022, Dar Ben-Natan and Mimi Ron ( HUJ 134766 !, HUJ 134769 !) ; Israel • Makhtesh Ramon, Ein Saharonim , 30. 3. 2023, Dar Ben-Natan ( TELA!) ; Israel • Arava valley, lower Ein-Gidron , coor: 30°47'46.4"N, 35°16'34.3"E, alt: 180 m. Hidden in the undergrowth at the S. bank of the wadi, near the eastern edge of the water stream, on wet, saline silt-grit. Probably parasitic on T. nilotica (Ehrenb.) Bunge. 14. Apr. 2024 Dar Ben-Natan and Mimi Ron ( HUJ! 1006364 !) ; Israel • Arava valley, lower Ein-Gidron , coor: 30°47'46.5"N, 35°16'33.8"E, alt: 180 m. Hidden in the undergrowth at the S. bank of the wadi, near the eastern edge of the water stream, on wet, saline silt-grit. Probably parasitic on T. nilotica (Ehrenb.) Bunge. 14. Apr. 2024. Dar Ben-Natan and Mimi Ron ( HUJ 1006365 !, HUJ 1006366 !, HUJ 1006367 !, HUJ 1006368 !, HUJ 1006369 !) .