28. Haloxylon Bunge, Reliq. Lehm. 292. 1851; (Mem. Sav. Etr. Petersb. 7: 468. 1851) Kom., Fl. URSS 6: 310. 1936; Jafri & Rateeb in Jafri & El-Gadi, Fl. Libya 95. 1978; Hedge in Rech. f., Fl. Iran. 172. 315. 1997.
Hammada Iljin in Bot. Zhurn. 33 (6): 582.1948; Arthrophytum auctt. p.p. non Schrenk in Bull. Cl. Phys.–Math. Acad. Imp. Sc. Petersb. 3: 211. 1845.
Small trees or shrubs, with spartioid branches, jointed, brittle stems and reduced or obsolete opposite leaves. Flowers borne on short twigs on lower part of older branches, perfect, 5-merous, with a pair of ± membranous bracteoles, solitary in the axils of scale-like bracts. Perianth segments membranous, free, with basal tufts of flexuose hairs, developing wings in fruit; stamens 5; anthers oblong-oval, unappendaged; filaments exserted, united at base into a hypogynous disc; staminodal lobes 5, thin, glabrous, not thickened. Ovary with 2-5 very short, ± sessile stigmas; seeds horizontal, with spiral embryo.
About 6 species, Central Asian; represented by 5 species in Pakistan.
It is not possible to separate Hammada Iljin and Haloxylon Bunge as the two genera often form a continuum in their characters. Consequently, Hedge (l.c., 1997) retained the broad generic circumscription of Haloxylon Bunge and included most of the taxa within it. We have also adopted the same broader circumscription and placed all our species under Haloxylon.
Some of our taxa have also been placed in the genus Arthrophytum Schrenk, but it is not possible to separate them from our generic circumscription of Haloxylon.