Common names: pai'i'iha (P. & E.)

Naturalized

Latin dentatus, toothed.

Plants medium-sized. Rhizomes short-creep-ing, around 0.7 cm diam. Fronds 50-100 cm long, fertile fronds generally longer and more erect than sterile ones. Stipes usually purple, sometimes straw-colored. Blades 1-pinnate-pinnatifid, lanceolate, narrowing at base, dark green and somewhat glossy adaxially, lighter abaxially; rachises usually purple, sometimes green or straw-colored, 20-33 pinna pairs before pinnatifid tips. Pinnae linear-lanceolate, 6-14 cm long, deeply lobed with 15-30 lobes, 3-6 proximal pinnae tapering and gradually becoming smaller, lowest pinnae reduced to 1/5-1/2 size of middle pinnae, to as small as 2 em long, tips acuminate, white hairs conspicuous, uniformly short, 0.2-0.4 mm long on adaxial surface, more and shorter hairs on abaxial surface, occasionally with scattered longer hairs, sinuses narrow, cut 112-2/3 to mid-rib, glands absent. Veins pinnate with 6-8 branches, only the basal pairs anastomosing once and forming excurrent veins to sinuses. Sori medial. Indusia present.

Very common in diverse habitats, 10-1,250 m, all major islands.

Widely distributed in the Tropics and sub-tropics of the Old World and spread widely as a weed in the Americas. Most common in disturbed mesic habitats, but also occurring in varied habitats including relatively undis-. turbed sites. The first alien fern reported to have become naturalized in Hawai'i, Christella dentata was first collected on O'ahu in 1887 and has since spread widely. It has been confused with C. parasitica, a closely related species. The two species frequently grow to-gether and sometimes hybridize; C. dentata also hybridizes with the endemic species C. cyatheoides, forming extensive clones of the sterile hybrid. (See discussion of hybrids later in this genus treatment.)

Christella dentata can be distinguished from C. parasitica by its lower pinnae being reduced gradually in size, its usually pur-ple stipes and rachises, darker and glossier fronds, shorter hairs, sparse or absent glands, and narrower sinuses.