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Sticherus Presl

Terrestrial ferns of moderate to large size with erect or scandent and thicket-forming fronds. Rhizome underground, long creeping, dichotomously branched, a single frond at the base of each fork, protostelic, apex bearing peltate scales. Fronds of indeterminate growth, with a permanently or periodically dormant apex producing a series of pairs of primary lateral branches along the rachis, often subtended by a pair of reduced, stipule-like leaflets, the primary branches may be pseudodichotomously divided with a dormant apex, into equal or unequal secondary branches that may be similarly divided to several orders, the ultimate determinate branches and higher order branches deeply pinnatifid, lobed almost to the costa, the ultimate segments oblong, margin entire or finely toothed, the veins free, once forked, pinnately arranged each side of an obvious costule. Sori several to each lobe, attached to a small receptacle on the acroscopic branch of a vein, exindusiate, paraphyses small stellate hairs or long-fringed scales; sporangia 2-5, large, sessile, annulus complete and oblique. Spores monolete or trilete, smooth and translucent.

Species in Papuasia

1a. Stipule-like leaflets, different from ordinary segments of lamina present at the branchings of the main rachis in fronds of mature size 2
Stipule-like leaflet absent 6
2a. Segments of lamina at right angles to costa or +/- deflexed; lower surface not conspicuously glaucous 3
Segments of lamina distinctly oblique ascending; lower surface distinctly glaucous S. erectus
3a. Segments of the lamina deflexed, the lower ones much so, thick with edges much revolute when dry, main rachis branches once or twice forked S. reflexipinnula
Segments of lamina not or little deflexed; main rachis branches often more than twice forked 4
4a. Forking of rachis branches equal or nearly so, not alternately unequal with the larger branches of successive forks forming an almost straight line 5
Forking of rachis branches unequal, the larger branches at successive forks alternately to the right and left, the axes of these larger branches in an almost straight line. S. milnei
5a. Scales on costules very abundant, spreading so as to almost cover the lower surface of the lamina; veins on lower surface strongly raised S. venosus
Scales on constules not persistently covering the lower surface of lamina; veins not so raised S. truncatus var. truncatus
6a. Margins of segments of lamina not distinctly toothed, even at apex 7
Margins of segments of lamina distinctly toothed, especially near the apex 12
7a. Only ultimate branches fully leafy, the penultimate without lamina or with few scattered segments 8
At least penultimate branches fully leafy, sometimes lower ones also 9
8a. Ultimate branches to 20 cm long S. pulcher
Ultimate branches 30-40 cm long S. pseudoscandens
9a. Lamina segments 3-5 mm long, 1-2 times as long as the distance between costules S. bolanicus
Lamina segments at least 8 mm long, 3-7 times as long as the distance between costules 10
10a. Lamina segments 8-15 mm long, 3-4 times as long as the distance between costules S. (hooglandii)
Lamina mostly more than 15 mm long, 4-7 times as long as the distance between costules 11
11a. Costules at 60-70 degress to costa; erect ground fern of open situations S. erectus
Costules almost perpendicular to costae; scrambling fern of forests and forest margins S. brassii
12a. Costules at c. 45 degrees to costae; margins toothed almost to the base of the segments S. flabellatus
Costules at a wide angle to costa (approaching perpendicular); margins toothed only near the apex of the segments S. hirtus

13

13a. Lower surface of costae of fully expanded ultimate branches scaly near the base only or more generally, the scales all about equal in size with rather rigid fringing hairs; no scales on costules, nor on veins, except when young S. hirtus var. candidus
Lower surface of costae persistently scaly almost throughtout, the scales of various sizes, often with a lax fringe; smaller scales also persistent on the costules, and sometimes scales or hairs on the veins 14
14a. Segments of lamina not abruptly narrowed above the base, separated by a narrow sinus S. hirtus var. virescens
Segments of lamina c.2 mm wide except at the very base, separated by sinuses 1-1.5 mm wide S. hirtus var. lanuginosus