Orthiopteris Copel.

Luong, Thien Tam, Hovenkamp, Peter H. & Sosef, Marc S. M., 2015, Revision of the fern genus Orthiopteris (Saccolomataceae) in Malesia and adjacent regions, PhytoKeys 53, pp. 39-71 : 43-44

Orthiopteris Copel.

Orthiopteris Copel., Bernice P. Bishop Mus. Bull. 59: 14. 1929a. Type: Davallia ferulacea T. Moore = Orthiopteris ferulacea (T. Moore) Copel.

Ithycaulon auct. non Copel., Univ. Cal. Publ. Bot. 16: 79. 1929b. Type: Davallia moluccana Blume = Ithycaulon moluccanum (Blume) Copel.

Orthiopteris See also Excluded names.

Description.

Rhizome erect, stout, forming a trunk (2-)20-50(-100) cm high, in cross section showing two complete rings of vascular bundles, partly covered with scales, roots inserted on all sides of the rhizome especially in the older parts. Rhizome scales appressed at base, mostly basifix, pseudopeltate to peltate, mostly narrow lanceolate with long attenuate tips, thick, stiff, brittle, dark brown. Fronds tufted, erect, monomorphic. Stipes (10-)30-70(-90) cm long, 0.4-0.8 cm thick (at base), scaly or slightly roughened due to scale traces towards base, greenish-brown. Lamina tri- to quadripinnate, anadromous, deltoid or lanceolate, gradually attenuate towards apex, (30-)100-150(-200) × (30-)40-60(-100) cm, herbaceous to papyraceous, bright-green to brownish-green when dry, abaxial surface sometimes with scattered small scales. Segments alternating, the acroscopic sides of all divisions larger than basiscopic sides, except for the first basiscopic pinnules of the lowest two pinnae; ultimate segments sessile or very short stalked, trapeziform, asymmetric at base, shallowly to deeply lobed. Rachis and costae grooved on adaxial surface, veins dichotomously forked, free. Sori terminal on veins, apical or lateral on the lobe, marginal to sub-marginal, reflexed or not when dry, funnelform, obovate or elliptic, formed by an outer indusium continuous with the lamina and an inner indusium, affixed at sides and usually with same colour as the vein. Sporangia (3-)5-15(-30) per sorus, immersed within indusium when young, exserted when mature. Annulus cells 16-24, more or less equal to distinctly unequal in size. Spores tetrahedral-globose, 25-38 µm in polar view, 20-25 µm in lateral view; perispore surface ornamented with branching sinuous ridges, exospore smooth or weakly scabrate.

Geographical distribution.

Orthiopteris has seven species occurring in the Malay-Pacific region, one of which is widespread in the area and consists of a number of geographically more or less weakly delimited varieties (Figure 7 ), the remaining six are more or less narrow endemics in the eastern part of the region (Figure 8 ). On Madagascar, there is a single species.

Key to the species

1	Ultimate segments of fronds finely dissected, distance from base of sinuses to the nearest costule 0.1 mm or less; lobes usually with a single unbranched vein, or with 1-2 additional veins	2
-	Ultimate segments of fronds not finely dissected, distance from base of sinuses to the nearest costule more than 0.1 mm (usually more than 0.5 mm); lobes with veins pinnately branched into more than 3 veins	5
2	Ultimate segments completely dissected to the veins, thus forming a single lobe for each vein, lobe not narrowed toward base; sori equal to or wider than the sterile lamina part below its base	3
-	Ultimate segments not completely dissected to the veins, with 2-3 veins per lobe, lobe narrowed towards base; sori narrower than the sterile lamina part below its base	4
3	Sori elliptic-obovate, not reflexed when dried; inner indusium extending into a narrow tongue. Plant including rhizome not more than 1 m tall; stipes slender, 1-2 mm thick	3. Orthiopteris ferulacea
-	Sori funnelform, reflexed when dried, inner indusium extending into a narrow tongue. Plant including rhizome more than 1 m tall; stipes thicker than 2 mm	8. Orthiopteris trichophylla
4	Outer indusium asymmetric; inner indusium lobed with lobe less than 2/3 width of sorus. Angle between ultimate segment and costa usually larger than 40°	2. Orthiopteris cicutarioides
-	Outer indusium symmetric; inner indusium obtuse, if lobed then lobe shallow and more than 2/3 width of sorus. Angle between ultimate segment and costa smaller than 40°	7. Orthiopteris tenuis
5	Lamina margin with distinct yellow cartilaginous border; inner indusium extending into a narrow tongue about half the length of the entire sorus; sori elliptic to obovate	4. Orthiopteris firma
-	Lamina margin without distinct yellow cartilaginous border; inner indusium not extending into a narrow tongue, but truncate or with a shallow, obtuse lobe (about 1/4-1/3 length of sorus); sori funnelform	6
6	Inner indusium distinctly shorter than outer, if almost equal then lamina thick and finely dissected	7
-	Inner indusium equal as or little shorter than outer, at least 2/3 as long; lamina thin and not finely dissected	8
7	Lamina 140-150 cm wide, as wide as long or wider, papyraceous, thin; ultimate segments stalked, wide trapeziform; veins darker than lamina; sori nearly as wide as long, fertile vein swollen at the joint with base of sori; inner indusium emarginate and irregularly eroded, not lobed	5. Orthiopteris henriettae
-	Lamina 40-50 cm wide, longer than wide, herbaceous, not thin; ultimate segments sessile or very short stalked, narrow trapeziform; veins lighter than lamina; sori 2/3 as wide as long; fertile vein not swollen at the joint with base of sori; inner indusium entire, forming a shallow lobe.	7. Orthiopteris tenuis
8	Abaxial surface of lamina with scattered irregular triangular scales; apex of inner indusium lobed and eroded. Sori situated on both acroscopic and basiscopic sides of lobes	6. Orthiopteris samoensis
-	Abaxial surface of lamina without scales or with few hair-like scales; apex of inner indusium often entire and obtuse to truncate, if single-lobed then sori situated mostly on acroscopic side of lobes	9
9	Sori asymmetric; inner indusium with single lobe; lobe width less than 2/3 width of sorus	10
-	Sori symmetric, inner indusium obtuse to truncate, if forming a lobe then lobe width at least 2/3 width of sorus	11
10	Sori 0.6 mm or more wide	12
-	Sori not wider than 0.6 mm	1d. Orthiopteris campylura var. insularis
11	Sori strongly reflexed when dry	1c. Orthiopteris campylura var. kingii
-	Sori in the plane of the lamina when dry	1a. Orthiopteris campylura var. campylura
12	Lobes of ultimate segments blunt, obtuse; sori longer than wide; outer indusium not confluent with lamina margin on one side but incised	1e. Orthiopteris campylura var. laxa
-	Lobules of ultimate segments acute; sori almost as wide as long; outer indusium confluent with lamina margin on one side	1b. Orthiopteris campylura var. caudata

Figures

Figure 7. Distribution of Orthiopteris excl. Saccoloma.

Figure 8. Distribution of Orthiopteris campylura and its varieties.