Manual of the New Zealand Flora.

[Introduction to Order XCIII. Filices.]

Perennial or very rarely annual plants, usually herbaceous but sometimes arboreous (tree-ferns). Stems generally reduced to a rhizome, which may be short and tufted, or long and creeping or climbing; or, in the case of tree-ferns, produced into an erect caudex or trunk. Leaves (fronds) either crowded at the end of the rhizome or distantly placed along it, continuous with the rhizome or jointed to it, sometimes simple and entire, but usually more or less deeply pinnately lobed or divided and frequently repeatedly so, more rarely dichotomously branched always circinate in vernation with the exception of the Ophioglossaceæ;.Spore-cases or sporangia usually arranged in groups (sori) on the under-surface or margins of the fertile fronds, which are either similar to the sterile fronds, or narrower and more contracted, the divisions sometimes becoming linear and spike-like. Sori very various in size and shape and position, naked or covered when young by the recurved margin of the frond or by a special involucre (indusium).Sporangia many or rarely few in a sorus, often mixed with jointed hairs or scales, stalked or sessile, usually furnished with a complete or incomplete ring or annulus, dehiscing by a transverse or vertical slit, free or rarely coherent into a compound sporangium (synangium).Spores numerous, bilateral or tetrahedral.

Ferns constitute one of the largest and most generally distributed of the families of plants, and are found in all quarters of the world, although most abundant in moist climates. It is difficult to estimate the number of species, on account of the divergent views of authors, but they cannot be less than 3500. In the subjoined account of the New Zealand species I have adopted the limitation of the genera proposed in Hooker and Baker's "Synopsis Filicum," that being the arrangement followed in the Handbook, Bentham's "Flora Australiensis," and other colonial floras, and the one acquiesced in by most English systematists. But European pteridologists as a rule accept a much larger number of genera, with a somewhat different sequence. And it must be admitted that Polypodium, Nephrodium, Asplenium, and other genera, as defined in the Synopsis, are for the most part artificial assemblages of species, possessing very diverse characters and relationships. But though it is comparatively easy to separate a group here and there as being undoubtedly worthy of generic rank, it is admittedly a matter of great difficulty to prepare good and natural generic subdivisions for the whole order, and although many attempts have been made not one of them has received a wide acceptance. The most recent classification is that given in Engler and Prantl's "Die Naturlichen Pflanzenfamilien," where the class Filicales is divided into 12 familes and 140 genera, against the 75 genera adopted in the "Synopsis Filicum." The 31 genera of New Zealand ferns are spread out into 42 in the Pflanzenfamilien.

The development of ferns can only be briefly alluded to here. In germination the spore produces a small flattened or rarely filamentous prothallium, usually containing abundant chlorophyll, but without vascular tissue. It becomes quite free from the spore, but is of comparatively short duration. On the under-surface of the prothallium the reproductive organs are formed. The male organs are called antheridia, and consist of minute subglobose bodies each containing numerous motile cells known as spermatozoids, resembling spirally coiled filaments, pointed at one end and bearing numerous cilia. The female organs, or archegonia, are flask-shaped bodies partly sunk in the tissue of the prothallium, each containing a single free cell called the oosphere. Fertilisation is effected by the entrance of spermatozoids into the cavity of the archegonium, and by the fusion of one of them with the oosphere. The oosphere then gradually develops into a young plant.

Since the publication of the Handbook several pamphlets or books dealing with the ferns of the colony have appeared. The most important of these are Mr. G. M. Thomson's "Ferns and Fern Allies of New Zealand" and Mr. H. C. Field's "Ferns of New Zealand." Both of these contain much interesting and valuable information, and should be consulted by all students of the order.

Suborder I. Hymenophyllacæ. Sori always marginal, enclosed within a cup-shaped or urceolate entire or 2-valved indusium. Sporangia sessile or shortly stalked, arranged on a short or long columnar receptacle, girt by a complete horizontal or oblique ring. Fronds membranous and translucent (except inLoxsoma).

Fronds membranous and translucent. Indusium deeply 2-valved 1. Hymenophyllum.
Fronds membranous and translucent. Indusium urceolate or trumpet-shaped, entire or shortly 2-lobed 2. Trichomanes.
Fronds coriaceous, opaque. Indusium urceolate, entire 3. Loxsoma.

Suborder II. Cyatheaceæ. Sori dorsal or marginal, naked or furnished with an indusium. Sporangia sessile or shortly stalked, arranged on a cushion-like receptacle, girt by a complete vertical or somewhat oblique ring. Stem-often arboreous.

Indusium globose, covering the young sorus, but soon bursting at the summit and persistent as a shallow cup surrounding the sorus at the base 4. Cyathea.
Indusium never covering the sorus, small, half cup-shaped or semicircular, one-sided, not forming a complete ring round the base of the sorus 5. Hemitelia.
Indusium altogether wanting 6. Alsophila.
Indusium 2-valved, the upper valve continuous with the margin of the frond 7. Dicksonia.

Suborder III. Polypodiaceæ. Sori dorsal or marginal, naked or furnished with an indusium. Sporangia with a short or long stalk, girt by an incomplete vertical ring, bursting transversely. Habit various.

*Indusium present, at least when the sorus is young.

† Sori dorsal or marginal. Indusium opening outwards, or towards the margin of the frond.

Sori globose or oblong, submarginal. Indusium often cup-shaped, attached by a broad base and sometimes by the sides as well 8. Davallia.
Sori subglobose, dorsal, remote from the margin. Indusium ovate-deltoid, membranous, attached by a broad base 9. Cystopteris.
Sori linear, marginal. Indusium linear, membranous, opening outwards. 10. Lindsaya.

†† Sori variable in shape, linear to globose, marginal. Indusium composed of the more or less modified edge of the frond, which is reflexed over the sorus, opening inwards.

Sori reniform or globose or oblong, distinct in the New Zealand species. Indusium an altered and reflexed lobe or tooth of the frond, bearing the sorus on its under-surface 11. Adiantum.
Sori subglobose, distinct, in the notches of the ultimate divisions of the frond. Indusium a slightly modified and reflexed portion of the margin of the frond 12. Hypolepis.
Sori subglobose or oblong, often confluent into linear masses. Indusium composed of the modified and reflexed margins of the frond. 13. Cheilanthes.
Sori confluent, forming a linear band extending along the greater part of the edge of the pinnæ, placed on the tips of the transverse veins 14. Pellæa.
Sori linear, extending along the greater part of the edge of the pinnæ or segments, placed on an intramarginal longitudinal vein 15. Pteris.
Sori linear, on the contracted pinnæ of fertile fronds differing much from the sterile ones, covering the whole under-surface. 16. Lomaria

††† Sori linear or oblong, dorsal (or submarginal when the frond is much divided). Indusium the same shape as the sorus, laterally attached to a vein, opening inwards (or towards the costa).

Sori oblong, on short cross veinlets connecting the primary veins, parallel to the costa. 17. Doodia.
Sori oblong or linear, on the primary veins, oblique to the costa. 18. Asplenium.

†††† Sori globose, dorsal. Indusium orbicular or reniform, peltate or affixed by the sinus, opening all round the margin.

Indusium orbicular and peltate 19. Aspidium
Indusium reniform and attached by the sinus. Fronds usually2–4-pinnate; pinnæ not articulated to the rhachis 20. Nephrodium.
Indusium reniform and attached by the sinus. Fronds pinnate pinnæ articulated to the rhachis 21. Nephrolepis.

** Indusium altogether absent.

Sori globose or broadly oblong, dorsal, distinct 22. Polypodium.
Sori oblong or rounded, at first distinct but ultimately confluent, marginal, often partly concealed by the reflexed margin of the frond and then barely distinguishable from Cheilanthes 23. Nothochlæna.
Sori oblong or linear, simple or forked, often confluent, dorsal 24. Gymnogramme.

Suborder IV. Gleicheniaceæ. Sori dorsal, naked, of few (2–6) sporangia receptacle not elevated. Sporangia sessile or nearly so, splitting vertically, surrounded by a complete transverse ring.

Fronds dichotomously forked ultimate branches pinnately divided 25. Gleichenia.

Suborder V. Schizæaceæ. Sporangia crowded, not collected into distinct sori, sessile or nearly so, with a complete transverse ring just below the apex, splitting vertically. Fertile portions of the frond much modified.

Fronds simple or forked or flabellately divided, without an expanded lamina. Sporangia in 2–4 rows on the under-surface of short linear fertile pinnæ terminating the fronds 26. Schizæa.
Fronds very long, climbing primary pinnæ dichotomously or pinnately divided. Sporangia in 2 rows on the under-surface of contracted fertile pinnules 27. Lygodium.

Suborder VI. Osmundaceæ. Sori irregular, distinct or confluent, dorsal; indusium wanting. Sporangia sessile or nearly so, splitting vertically; ring rudimentary, placed just below the apex.

Fronds opaque or translucent, 2–3-pinnate 28. Todea.

Suborder VII. Marattiaceæ. Sori distinct, dorsal. Sporangia sessile, without any ring, coriaceous, splitting vertically or opening by a pore at the apex, usually cohering in concrete masses called synangia.

Rhizome large, tuberous. Fronds large, 2–3-pinnate 29. Marattia.

Suborder VIII. Ophioglossacæ. Sporangia globose, coriaceous, sessile, without any ring, dehiscing by a transverse or vertical slit, crowded on a linear spike or on the branches of a panicle. Fronds not circinate in vernation.

Sterile frond simple and entire. Sporangia on a linear spike 30. Ophioglossum.
Sterile frond pinnate or 2–4-pinnate. Sporangia on the linear branches of a panicle 31. Botrychium.