Classification
 Subordinate Taxa
 Nomenclature
Scientific Name:
Christella H.Lév., Fl. Kouy-Tcheou 472 (1915)
Type Taxon:
Christella parasitica (L.) H.Lév.
Etymology:
Named in honour of K.H.H. Christ (1833–1933), Swiss pteridologist and Professor of Botany at Basel
 Description

Terrestrial ferns. Rhizomes erect to short- or long-creeping, scaly. Rhizome scales narrowly ovate, setiferous. Fronds monomorphic. Stipes hairy. Laminae 1-pinnate-pinnatifid, herbaceous, usually with 1–5 pairs of lower pinnae gradually reduced in size to c. 20 mm long; basal pinnae auricled acroscopically; aerophores at base of pinnae not swollen; abaxial surface of laminae lacking scales, usually bearing erect acicular hairs, often bearing short capitate hairs, and sometimes bearing thick red or orange glandular hairs (not NZ), lacking sessile spherical glands. Veins free (not NZ) or one or more basal veins from adjacent pinna lobes uniting below the sinus (NZ). Sori round, indusiate; paraphyses absent. Indusia reniform, bearing acicular hairs. Sporangia lacking glands or hairs near annulus, but bearing an elongate, unicellular, glandular hair on the stalk. Spores monolete, tuberculate or ridged.

 Taxonomy

Allan (1961) included all New Zealand species of Thelypteridaceae within a broadly construed Thelypteris. Holttum (1976) recognised Christella as a distinct genus of Thelypteridaceae with about 50 species, mostly in the Old World tropics, and one species in New Zealand. He distinguished the genus principally by the presence of an elongate, unicellular, thick, blunt hair on the stalks of the sporangia (Holttum 1971a). In addition, the lower pinnae are gradually reduced, the aerophores at the base of the pinnae are not swollen, acicular hairs are usually present on both surfaces of the lamina, short capitate hairs are often present, thick red or orange glandular hairs are sometimes present (but not in New Zealand), sessile spherical glands are absent, the basal veins from adjacent pinnules usually join, and the sori are indusiate (Holttum 1977). Smith et al. (2006) included Christella within a broadly circumscribed Cyclosorus, but Holttum’s classification is followed here for consistency (see Taxonomy under Thelypteridaceae).

 Distribution

A genus of c. 50 species distributed in the tropics and subtropics of the Old World and one extending to tropical America (Holttum 1976); five species in Australia (Bostock 1998) and 18 in the Pacific (Holttum 1977). Christella dentata is naturalised in the New World (Smith 1971; Holttum 1976) and Hawai‘i (Palmer 2003). One species in New Zealand; not endemic.

 Biostatus
Indigenous (Non-endemic)
Number of species in New Zealand within Christella H.Lév.
CategoryNumber
Indigenous (Non-endemic)1
Total1
 Cytology

The base chromosome number in Christella is x = 36 (Holttum 1977; Smith 1990).

 Notes

Holttum (1971b) accepted Léveillé’s earlier name, Christella, for a genus that he was then in the process of recognising. He selected C. parasitica (L.) H.Lév. as the type of the genus and redefined some of the characters.

Davison (1995) investigated Christella in New Zealand for an M.Sc. at the University of Auckland, but the results of her work have never been published.

 Bibliography
Bostock, P.D. 1998: Thelypteridaceae. In: Flora of Australia. Vol. 48. 327–358.
Davison, A.C. 1995: Studies on the genus Christella Léveillé in New Zealand. Unpublished M.Sc. thesis, University of Auckland.
Holttum, R.E. 1971a: Studies in the family Thelypteridaceae III: a new system of genera in the Old World. Blumea 19: 17–52.
Holttum, R.E. 1971b: Typification of the fern-genus Christella Léveillé. Taxon 20: 533–535.
Holttum, R.E. 1976: The genus Christella Léveillé, sect. Christella. Studies in the family Thelypteridaceae, XI. Kew Bulletin 31: 293–339.
Holttum, R.E. 1977: The family Thelypteridaceae in the Pacific and Australasia. Allertonia 1: 169–234.
Kramer, K.U.; Green, P.S. 1990: Pteridophytes and gymnosperms. Kubitzki, K. (ed.) The Families and Genera of Vascular Plants. Vol. 1. Springer-Verlag, Berlin.
Léveillé, A.A.H. 1915: Flore du Kouy-Tchéou. Lithographed from hand-written manuscript, Le Mans.
Palmer, D.D. 2003: Hawai‘i’s ferns and fern allies. University of Hawai‘i Press, Honolulu.
Smith, A.R. 1971: Systematics of the neotropical species of Thelypteris section Cyclosorus. University of California Publications in Botany 59: 1–143.
Smith, A.R. 1990: Thelypteridaceae. In: Kramer, K.U.; Green, P.S. Pteridophytes and gymnosperms. Vol. 1. In: Kubitzki, K. (ed.) The Families and Genera of Vascular Plants. Springer-Verlag, Berlin. 263–272.
Smith, A.R.; Pryer, K.M.; Schuettpelz, E.; Korall, P.; Schneider, H.; Wolf, P.G. 2006: A classification for extant ferns. Taxon 55(3): 705–731.