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Manual of the New Zealand Flora.

11. Adiantum, Linn

11. Adiantum, Linn.

Rhizome creeping or tufted. Stipes usually long, often black and glossy. Fronds pinnate or 2–3-pinnate, never pinnatifid, rarely simple (in a few species not found in New Zealand). Pinnules more or less dimidiate or unilateral. Veins forked or repeatedly dichotomous, frequently radiating from the petiole to the margin. Sori marginal, varying in shape from reniform or globose to oblong or linear, usually numerous and distinct, sometimes confluent and continuous. Indusium the same shape as the sorus, composed of the altered margin of the frond, which is reflexed and bears the sporangia on its under-side, opening inwards. Sporangia stalked, bursting transversely ring vertical, incomplete.

A well-marked genus of about 80 species, found in all tropical and subtropical countries, but most abundant in tropical South America, a few species found in the temperate zones of both hemispheres. All the New Zealand species extend to Australia, and the majority to the Pacific islands as well, while one has a very wide distribution in warm climates generally.

A. Pinnules flabellate-cuneate., attached by the middle of the base.
Fronds 2–3-pinnate, thin and membranous, glabrous. Pinnules small, orbicular with a cuneate base 1. A. œthiopicum.

B. Pinnules one-sided, obliquely oblong or rhomboid, attached by the lower corner of the frond.

* Sori in the deep notches between the teeth or lobules of the pinnules.
Fronds small, tender, simply pinnate or with 1–2 branches at the base. Pinnules sparsely setulose, rarely glabrous 2. A. diaphanum.
Fronds dichotomous, each division flabellately divided into 3–7 branches. Rhachis densely hispid 3. A. hispidulum.
** Sori in shallow excavations at the tips of the lobules of the pinnæ, not in the notches between the lobules.
Fronds very large and compound, 3–5 ft. high with the stipes. Rhachis pubescent above. Pinnules small, ¼–½ in. Sori transversely oblong 4. A. formosum.
Fronds 1–2 ft. with the stipes. Rhachis smooth, polished. Pinnules ½-l in., not falcate, glaucous beneath 5. A. affine.
Fronds 1–2 ft. with the stipes. Rhachis and costæ clothed with fulvous hairs. Pinnules ½–¾ in., subfalcate, frequently setulose, not glaucous beneath 6. A. fulvum.
1.A. æthiopicum,Linn. Sp. Plant. 1560.—Rhizome creeping, stoloniferous. Stipes 4–10 in. long, very slender, dark chestnut-brown, shining, quite glabrous. Fronds 6–12 in. long, rarely more, page 9613–6 in. broad, oblong to oblong-ovate or oblong-deltoid, erect or drooping, pale-green, very thin and membranous, flaccid, quite glabrous, 3–4-pinnate; rhachis very slender, almost capillary, flexuous, polished. Lower pinnæ 2–4 in. long, ovate-deltoid. Pinnules on rather long and slender petioles, not dimidiate, ¼—⅓ in. long, often broader than long, variable in shape, usually suborbicular with a more or less cuneate base, upper margin broadly and shallowly lobed. Pinnules of barren fronds often larger, entire or obscurely lobed. Sori 2–6 to a pinnule, placed in the notches or sinuses between the lobes. Indusium rather large, reniform or transversely oblong, pale.—Hook. Sp. Fil. ii. 37, t. 77A; Hook.f. Fl. Nov. Zel. ii. 21; Handb. N.Z. FL 360 Hook. and Bak. Syn. Fil. 123; Benth. Fl. Austral. vii. 724; Thoms. N.Z. Ferns, 54; Field, N.Z. Ferns, 83, t. 17, f. 1. A. assimile, Swartz, Syn. Fil. 125, 322. Raoul, Choix, 38. A. trigonum, Labill. Pl Nov. Holl. ii. 99, t. 248 Raoul, Choix, 38.

North Island Plentiful in lowland districts from the North Cape to the Thames and Waikato Rivers, from thence rare and local to Hawke's Bay (Colenso!) and Taranaki (H. C. Field!). South Island: Has been reported! from Nelson and Canterbury, but I have seen no specimens.

An abundant fern in most tropical and subtropical countries.

2.A. diaphanum,Blume, Enum. Fil. Jav. 215.—Rhizome very short, tufted; rootlets long, fibrous, densely tomentose, bearing; numerous small oblong tubers. Stipes 2–6 in. long, very slender, almost capillary, wiry, glabrous or slightly scaly towards the base, dark purplish-brown or almost black. Fronds 3–6 in. long, rarely more, simply pinnate, or with 1–2 branches at the base which are sometimes almost as long as the central portion but usually much shorter, thin and membranous, flaccid, dark-green branches ½—1 in. diam. Pinnules numerous, shortly petiolate, ⅓–½ in. long, about ¼ in. deep, dimidiate-oblong lower margin straight or more or less decurved, entire; upper margin about parallel, and together with the rounded apex deeply crenate-toothed; surfaces sparingly setulose with minute stiff black hairs. Sori 4–8 to a pinnule, rarely more, placed in the notches of the upper and outer margins. Indusium reniform, pale, minutely setulose.—Hook. Sp. Fil. ii. 10, t. 80c Hook, and Bak. Syn. FiL 117; Thoms. N.Z. Ferns, 53; Field, N.Z. Ferns, 80. t. 13, f. 5. A. affine, Hook. Sp. Fil. ii. 32; Hook. f. Fl. Nov. Zel. ii. 20; Handb. N.Z. FL 360 (not of Willd.). A. setulosum, J. Sm. in. Bot. Mag. Comp.(1846) 22.

Var. polymorphum, Cheesem.—Fronds smaller, pale-green, usually simply pinnate, rarely branched at the base. Surfaces of the pinnæ and indusia quite glabrous.—A. polymorphum, Col. in Trans. N.Z. Inst. xx, (1888) 215. A. tuberosum, Col. l.c. 217.

Kermadec Islands, North Island: Not uncommon in woods at low elevations, usually in rich alluvial soils. South Island: Apparently rare and page 962local. Nelson—Bateman's Gully, D. Grant;Collingwood, H. H. Travers,Canterbury—Gorge of the Rakaia, Potts.Otago—Various localities, Buchanan, Kirk.Sea-level to 1000 ft.

Also in Norfolk Island, east Australia, Fiji, New Caledonia, New Hebrides, Java, and southern China.

3.A, hispidulum,Swartz, Syn. Fil. 124, 321.—Rhizome short, stout, creeping. Stipes 6–15 in. long, stout, erect, scabrous, dark-brown or almost black, more or less clothed with short greyish-white pubescence when young, becoming almost glabrous when old. Fronds broad, 6–12 in. or more across, dichotomously forked at the base, both forks irregularly flabellately divided into 3–7 linear secondary divisions 3–8 in. long by ½–¾ in. broad, colour olive-green, often red or reddish-brown when young, rhachises densely hispid-pubescent. Pinnules numerous, closely placed, petiolate, ⅓–⅔ in. long, about ¼ in. deep, dimidiate, rhomboidal, rigid, prominently nerved, more or less hispid, especially on the under-surface, upper margin and the obtuse tip finely toothed, lower margin entire. Sori numerous on each pinnule, contiguous, placed in the notches of the upper and outer margins. Indusium orbicular-reniform, minutely hispid.—A. Rich, Fl. Nouv. Zel. 88 A. Cunn. Precur. n. 209; Raoul, Choix, 38 Hook. Sp. Fil. ii. 31; Hook. f. Fl. Nov. Zel. ii. 20 Handb. N.Z. Fl. 360 Hook, and Bak. Syn. Fil. 126; Benth. Fl. Austral. vii. 725; Thoms. N.Z. Ferns, 55; Field, N.Z. Ferns, 82, t. 13, f. 1. A. pubescens, Schkuhr Fil. 108, t, 116; A. Rich. Fl. Nouv. Zel. 89. A. pedatum, Forst. Prod. 458 (not of Linn.).

Kermadec Islands, North Island: Abundant as far south as the East Cape and Raglan, from thence somewhat rare and local to Cook Strait. South Island Nelson—Bishopdale, D. Grant.

The rather harsh hispid-pubescent fronds distinguish this from all the other New Zealand species. Outside New Zealand, it extends through the Pacific islands and Australia to tropical Asia and Africa.

4.A. formosum,R. Br. Prodr. 155.—Rhizome long, stout, creeping, scaly. Stipes 1–3 ft. high, dark purplish-black or quite black, shining, sometimes hairy towards the base, scabrous throughout. Fronds 1½–3 ft. long, 12–20 in. broad, broadlv deltoid, dark-green, copiously 3–4-pinnate; main rhachis flexuous, black, glossy, glabrous or pubescent; secondary rhachises usually pubescent. Lower pinnæ large and broad, often 12–15 in. long, ascending, very compound; secondary pinnæ usually again divided. Pinnules very numerous; fertile small, ¼–½ in. long, ⅕–¼ in. deep, petiolate, dimidiate, broadly obliquely-oblong or rhomboid; lower margin straight or slightly hollowed, entire, upper and the rounded outer margin deeply toothed or incised; texture firm; under-surface glabrous or pubescent with scattered white hairs. Pinnules of the barren frond larger, often page 963¾ in. long or more, more membranous, upper and outer margins-deeply lobulate, the lobules incised. Sori numerous, placed in shallow depressions at the top of the teeth or lobules, broader than long, transversely oblong or oblong-reniform.—Hook. Sp. Fil. ii. 51, t. 86B Hook, f. Fl. Nov. Zel. ii. 21; Handb. N.Z. Fl. 360 Hook, and Bak. Syn. Fil. 119 Benth. Fl. Austral. vii. 724 Thoms. N.Z., Ferns, 54; Field, N.Z. Ferns, 81, t. 6.

North Island: Auckland—Alluvial banks of the northern Wairoa River, from Tangiteroria to a few miles above Dargaville, T. F. C.Wellington— Manawatu River and its tributaries, from Woodville to below Palmerston North,. Colenso! Enys! Field! Hamilton!&c.

Also a native of eastern Australia. Easily recognised by its large size, decompound fronds, and numerous small somewhat rigid pinnules.

5.A. affine,Willd. Sp. Plant, v. 448.—Rhizome long, creeping, stout, clothed with glossy dark chestnut-brown scales. Stipes-4–12 in. long or more, stout, erect, shining-black, rough and scaly at the very base, smooth and polished above. Fronds 6–15 in. long. 3–9 in. broad, ovate-deltoid in outline, bipinnate or tripinnate at the base, pale-green above, usually glaucous beneath, quite-glabrous or the secondary rhachises pubescent above. Pinnæ 2–3 pairs with a long terminal one sometimes 6–9 in. long, in large specimens the lowest pair again branched. Pinnules ½–1 in. long, ¼—½ in. deep, petiolate, dimidiate, broadly obliquely-oblong or rhomboidal lower margin straight, entire, base truncate; upper margin and the obtusely rounded apex deeply crenate-toothed; texture firm, subcoriaceous. Sori numerous, rather large, 6–14 to a pinnule, placed in small notches at the tips of the lobes of the upper and. outer margins, not in the sinuses between the lobes. Indusium orbicular-cordate or reniform.—Hook, and Bak. Syn. Fil. 117; Benth. Fl. Austral. vii. 724 Thoms. N.Z. Ferns, 53 Field, N.Z. Ferns, 80, t. 6, f. 1. A. Cunninghamii, Hook. Sp. Fil. ii. 52, t. 86A Hook. f. Fl. Nov. Zel. ii. 21 Handb. N.Z. Fl. 360. A. formosum, A. Rich, Fl. Nouv. Zel. 88 A. Cunn. Precur. n. 208; Raoul, Choix, 38 (not of R. Br.).A. pullum, Col. in Trans. N.Z. Inst. xxv. (1873) 319.

Kermadec Islands, North and South Islands, Stewart Island,. Chatham Islands: Abundant in lowland districts throughout.

Also in Australia, according to Bentham (Fl. Austral, vii. 724). Very variable in size, the amount of branching of the frond, and in the size and shape of the pinnules. When growing on exposed rock-faces it is often dwarfed to an inch or two. Most of the Chatham Islands specimens that I have seen are less compound, with larger and coarser narrower pinnules, corresponding, I presume, with the variety Chathamicum of Mr. Field (N.Z. Ferns, 81). A curious form gathered by Mr. Hamilton on limestone crags at Moteo, near Puketapu, Hawke's Bay, has the tips of the pinnæ largely cristate, and the pinnules very irregular in shape. It is the A. Cunninghamii var. heterophyllum of Colenso (Trans. N.Z. Inst. xx. (1888) 218). States with the secondary rhachises somewhat pubescent above, and with rather narrower and more acute-, pinnules, seem to show a marked approach to A. fulvum.

page 964
6.A. fulvum,Raoul, Choix de Plantes, 9.—Rhizome long, creeping, clothed with brownish subulate scales. Stipes 4–12 in. long, erect, dark reddish-brown or almost black, rough with minute projections throughout, more or less scaly towards the base. Fronds 6–15 in. long. 3–9 in. broad, ovate-deltoid in outline, 2–3-pinnate or rarely in large specimens 4-pinnate at the base, olive-green or pale-green, not glaucous beneath; rhachis and costæ more or less densely clothed above with strigose fulvous hairs. Pinnæ 2–4 pairs with a long terminal one, in small specimens not branched, in larger ones the lowest pair and sometimes all again divided, or rarely the lowest pair twice branched. Pinnules ½–¾ in. long, about ¼ in. deep, petiolate, dimidiate, obliquely oblong, often slightly falcate; lower margin curved or nearly straight, entire; upper margin almost parallel, deeply crenate lower surface often minutely setulose with stiff fulvous hairs texture firm but not coriaceous. Sori usually numerous in shallow notches at the tips of the lobes of the upper and outer margins, not in the sinuses between the lobes. Indusium orbicular-cordate, often pale when young.—Hook. Sp. Fil. ii. 52, t. 85A Hook. f. Fl. Nov. Zel. ii. 22 Handb. N.Z. Fl. 361; Hook, and Bak. Syn. Fil. 120 Thorns. N.Z. Ferns, 54; Field, N.Z. Ferns, 81, t. 6, f. 4. A. viridescens, Col. in Trans. N.Z. Inst. xxvii. (1895) 400.

North and South Islands Lowland districts as far south as Banks Peninsula, not uncommon.

Very close indeed to A. affine, with which it certainly seems to me to be connected by intermediate forms. It is more copiously branched, the rhachis and costæ are clothed with strigose fulvous hairs, the stipes is minutely muricate, and the pinnules are narrower and subfalcate, and often setulose beneath. It is also found in Norfolk Island, New South Wales, and Fiji.