Jackiellaceae R.M.Schust.
Jackiellaceae R.M.Schust., J. Hattori Bot. Lab. 36: 395. 1972.
Cephaloziaceae subfam. Jackielloideae R.M.Schust., Hepat. Anthocerotae N. Amer. 3: 649. 1974.
Type: Jackiella Schiffn.
Plants closely creeping to prostrate, usually deep brown to fuscous, compact and firm, xeromorphic, small. Branching sparing, either exclusively ventral- or lateral-intercalary from the ventral angle of lateral leaves; stolons lacking. Stem rigid, the cortex ill-defined, a hyaloderm lacking, the cortical and medullary similar, ± firm-walled. Rhizoids freely developed, in fascicles at or near underleaf bases or from small cushions or swellings where underleaves have been suppressed. Leaves with insertion strongly succubous, the lines of insertion not extending to stem midline dorsally, the leaves alternate, concave, ± ovate to broadly ovate-triangular to suboblate and with a rounded apex, the ventral margin dilated toward base, the leaves unlobed, the apex and margins entire. Cells strongly collenchymatous, trigones nodular to nodose-triradiate, the trigones separated by narrow, thin-walled places; surface smooth. Oil-bodies (Jackiella curvata) occupying conspicuous portion of cell lumen, 2(3) per cell, very pale brown, finely granular. Underleaves absent or vestigial, minute, obscure, lamella-like or consisting of 2–3 cilia, each comprised of a uniseriate row of a few cells and terminating in a slime papilla. Asexual reproduction by 2-celled gemmae.
Dioecious. Androecia on abbreviated, determinate, ventral-intercalary branches, minute, slenderly spicate; bracts in up to 25 or more pairs, small, ventricose, unlobed, the apex and margins entire; antheridia 1 per bract, the stalk short, uniseriate, the jacket-cells tiered, elongate; bracteoles absent. Gynoecia on abbreviated ventral-intercalary branches lacking normal vegetative leaves, developing a pendent, massive, rhizoidous, cylindrical marsupium, the summit with a pair of bractlets but a distinguishable bracteole lacking; perianth absent.
Sporophyte foot small, conoidal, the haustorial collar with slender, rhizoid-like, septate filaments. Seta with 8 rows of outer cells surrounding a ring of 7–8 internal cells much smaller in size and a central core of 3–4 rows of cells somewhat smaller than the subepidermal ring. Capsule long-ellipsoidal (ca. 2.3:1), the valves straight, linear, 2-stratose, the outer layer subequal to the inner layer or the inner a little thicker; outer layer of cells with one-phase development, ± tiered, short-rectangular, with strong sheet-like pigmented thickenings on all radial-longitudinal walls, the thickenings at times weakly sinuous, but nodular thickenings lacking, the transverse walls devoid of thickenings; inner layer of cells ± tiered, short-rectangular, with semiannular bands, the bands complete or, often, thin or incomplete in middle of tangential wall.
Spores minute, nearly smooth, less than elaters in diam. Elaters ± straight, rigid, bispiral.
A family with one genus of ca. six species. The genus ranges from Indonesia to Indomalaya to Southeast Asia. Jackiella javanica Schiffn. ranges from New Guinea to Indonesia to Japan; J. sinensis (W.E.Nicholson) Grolle occurs in Yunnan, China. One species occurs in New Zealand.
