Taeniopteris.

This generic name was instituted by Brongniart[1254] for simple linear or broadly linear leaves with a prominent midrib from which secondary veins, simple or dichotomously branched, are given off at right angles or obliquely. The frond of the type-species Taeniopteris vittata ([fig. 332]), characteristic of Jurassic floras, was compared by Brongniart with the pinnules of Danaea and Angiopteris. Among recent ferns the Taeniopteris form of frond and venation is represented by Oleandra neriiformis, Asplenium nidus, and many other species. Though usually applied to fronds which there is good reason for regarding as simple leaves, the generic designation Taeniopteris has been extended to include pinnate fronds, e.g. the Upper Palaeozoic species T. jejunata Grand’Eury, and T. Carnoti Ren. and Zeill. ([fig. 330], A). The compound fronds from the Lower Coal-Measures of Missouri described by Dr White[1255] as T. missouriensis are characterised by decurrent and confluent Taeniopteroid pinnules. In a later reference[1256] to this plant White pertinently adds, “perhaps it belongs more properly in Alethopteris.”

Leaves of the Taeniopteris type are described by several authors as species of Oleandridium, Angiopteridium, Danaeites, Marattia, and other genera. In such species of Taeniopteroid leaves as have been dealt with in a former Chapter, the occurrence of sori justifies the substitution of a name denoting a close relationship to existing members of the Marattiaceae, but in the absence of fertile specimens the provisional designation Taeniopteris should be retained. It is often difficult to decide between Taeniopteris and Nilssonia as the more suitable name to apply to fragments of fossil leaves of Mesozoic age. Taeniopteris is, however, distinguished from the Cycadean genus by the greater prominence of the rachis, also by the dichotomous branching of the secondary veins, usually close to their origin and at varying distances between the axis of the frond and the edge of the lamina. The genus Taeniopteris, though most abundant in Rhaetic and Jurassic strata, occurs also in Upper Carboniferous and Lower Permian rocks. The generic name Macrotaeniopteris instituted by Schimper[1257] has been used for leaves differing only in size from the usual type of Taeniopteris, but there is no adequate reason for its retention.

The species included in Taeniopteris afford no satisfactory evidence as to their systematic position. It is obviously unwise to adopt such generic titles as Oleandridium, Marattiopsis, etc., merely because of resemblance in the venation of sterile fragments to Oleandra or Marattiaceous ferns.

Some specimens of Taeniopteris fronds described by Mr Sellards[1258] from Permian rocks of Kansas, which are referred to later, have furnished unconvincing evidence of reproductive organs.

Taeniopteris multinervis, Weiss. Fig. 329, A, B.

The late Dr Weiss[1259] instituted this species (which he designated Taeniopteris multinervia, though the specific name multinervis is constantly used) for a fragment of a leaf from the Lower Permian of Lebach characterised by numerous forked veins given off at right angles from a prominent rachis ([fig. 329], B). This type of frond is recorded from the Permian of Trienbach (Alsace) by Zeiller[1260], by Renault[1261] and Zeiller[1262] from the Upper Carboniferous of Autun, and from other localities. The lamina of the simple leaf reaches a breadth of 6 cm. and a length of 40 cm. ([fig. 329], A); the numerous secondary veins (25–36 per cm. of lamina) are either at right angles to the rachis or given off at an acute angle. The mesophyll consists of polygonal cells some of which are elongated at right angles to the surface of the lamina. A very similar form is described by Fontaine and White from the Permian of Virginia as T. Lescuriana[1263].

Fig. 329.

Taeniopteris multinervis, Weiss. (⅚ nat. size. After Zeiller.)
T. multinervis. (Enlarged. After Zeiller.)
Lesleya Delafondi. (× 2. After Zeiller.)

It is futile to expect to be able to separate the numerous Taeniopteris leaves into well-defined species: all we can do is to group the specimens under different names, using as artificial distinctions such characters as the shape of the leaf, the number of veins per centimetre, and the prominence of the rachis. Another Virginian species of Permian age described by Fontaine and White[1264], T. Newberriana, is said to bear sori, but no satisfactory information is given as to the nature of these organs. Specimens referred with some hesitation to this species and to a similar species, T. coriacea, have been described by Sellards[1265] from material obtained from Permian beds in Kansas. The lamina of the simple linear fronds is characterised by the occurrence of small oval bodies half immersed in the substance of the leaf between the secondary veins ([figs. 330], D, E). One of these bodies is represented in an apparently dehisced condition in [fig. 330], D. Sellards suggests the possibility that these bodies are sporangia, but, as he points out, they afford no indication of cellular structure nor are they in direct connexion with the veins.

Taeniopteris jejunata, Grand’Eury[1266].

This species differs from T. multinervis in its bipinnate fronds; the linear or oval-linear pinnae are attached by a short stalk to the primary rachis and reach a length of 25 cm.; the veins are less crowded, 12–15 per centimetre.

T. jejunata is recorded from the Coal-fields of the Loire and Commentry[1267] in France, from the Lower Permian of Thuringia[1268], and elsewhere.

Taeniopteris Carnoti, Ren. and Zeiller[1269]. Fig. 330, A.

This species, founded on portions of pinnate fronds from the Coal-field of Commentry, is characterised by rather broader (25–30 mm.) pinnules, with short pedicels and a cordate base, reaching a length of 25–30 cm. The secondary forked veins are more numerous than in T. jejunata. In T. multinervis the pinnules are still broader and have a stronger midrib.

•••••

Several species of Taeniopteris have been described from Triasso-Rhaetic rocks in Europe, India, Tonkin and elsewhere. In some cases it is practically impossible to recognise clear specific distinctions between Rhaetic and Jurassic types.

From the Damuda and Panchet series of India (Triasso-Rhaetic) Feistmantel has described large sterile fronds as Macrotaeniopteris Feddeni[1270] which reach a breadth of 20 cm.: these may be compared with the Indian species Taeniopteris lata Oldham[1271], and to T. gigantea from the Rhaetic of Franconia[1272] and Scania. A specimen of this species figured by Nathorst[1273] from Scania has a lamina 33 cm. broad. Other examples are afforded by M. Wianamattae Feist.[1274] from rocks of the same age in Australia and by Taeniopteris superba Sap.[1275] from Lower Rhaetic rocks near Autun.

From the Rhaetic of Tonkin, Zeiller records several species, among which may be mentioned T. Jourdyi Zeill.[1276] and T. spatulata MacClelland ([fig. 330], B, C). Both have simple fronds. Those of T. Jourdyi reach a length of 10–40 cm. and a breadth of 10–70 mm.; the rachis is characterised by crowded and discontinuous transverse folds, and the secondary veins (35–50 per cm.) are usually at right angles to the rachis. This Tonkin species is compared by Zeiller with the European Rhaetic species T. tenuinervis Brauns.

The polymorphism of the fronds is a striking feature: in one case described by Zeiller the lamina appears to be divided into segments like those characteristic of the leaf of the Cycadean genus Anomozamites. It is obviously difficult in many instances to distinguish between detached Taeniopteroid pinnae of a compound frond and complete simple leaves. In some compound fern fronds, as in the recent Polypodiaceous genus Didymochlaena, the pinnules are deciduous, and the same feature undoubtedly characterised the fronds of many extinct species. A specimen figured by Zeiller which shows several petioles of T. Jourdyi attached to a thick stem[1277] demonstrates the simple nature of the leaves. In other cases, e.g. T. vittata, specimens occur in which the slightly enlarged petiole-base has a clean-cut surface indicating abscission from a rhizome ([fig. 332]).

The fronds described by Zeiller as T. spatulata[1278] ([fig. 330], B, C) closely resemble Jurassic leaves from Victoria referred to Taeniopteris Daintreei McCoy[1279].

Fig. 330.

Taeniopteris Carnoti, Ren. and Zeill. (Nat. size. After Renault and Zeiller.)
T. spatulata, McClell. (Nat. size. After Zeiller.)
T. spatulata. (× 3. After Zeiller.)
Supposed sporangium of T. coriacea. (× 15. After Sellards.)
T. coriacea. (× 2. After Sellards.)

Whether specifically identical or not, these leaves represent a type distinguished from the other species of the genus by the small breadth of the linear-lanceolate or linear-spathulate lamina, which may be 6–15 cm. in length and 3–12 mm. broad. The lamina is often characterised by transverse folds ([fig. 330], C).

Taeniopteris Carruthersi. Fig. 331.

1872.	Taeniopteris Daintreei, Carruthers, Quart. Journ. Geol. Soc. Vol. XXVIII. Pl. XXVII. fig. 6.
1883.	T. Carruthersi, Tenison-Woods, Proc. Linn. Soc. N. S. Wales, Vol. VIII. p. 117.

Fig. 331. Taeniopteris Carruthersi, Ten.-Woods. Nat. size.

The simple fronds included under this specific name are characterised by a strong midrib from which numerous simple or forked secondary veins are given off at a right angle or slightly inclined. The breadth of the lamina decreases gradually towards the petiole. The Australian species named by McCoy Taeniopteris Daintreei, to which Carruthers referred the Queensland fossils, has a much narrower and more linear form of frond, and for this reason Tenison-Woods instituted a new specific name. T. Carruthersi represents a form of leaf met with in Rhaetic, or possibly Upper Triassic, rocks in S. Africa[1280] and Australia. A very similar, perhaps an identical type, was described from Argentina by Geinitz[1281] as T. mareyiaca: among many other examples of this form of frond may be mentioned T. immersa[1282] Nath. from the Rhaetic rocks of Scania and T. virgulata from the Rhaetic of Tonkin[1283].

A comparison of Taeniopteris Carruthersi or various other “species” of Rhaetic fronds with the Jurassic species T. vittata illustrates the slight and unimportant differences on which specific separation is based. It is hopeless to attempt to draw a satisfactory distinction between the numerous Taeniopteris fronds from Upper Triassic and Jurassic rocks.

Taeniopteris vittata, Brongniart. Fig. 332.

The simple leaves to which Brongniart applied this name are characteristic of the Inferior Oolite flora of England, and examples of the same type are recorded from Jurassic rocks of India, Poland, the Arctic regions, Japan, China, Australia and other countries[1284].

Leaf linear-lanceolate, reaching a length of more than 20 cm. and a breadth of 3 cm. The lamina increases gradually in breadth from the base and tapers towards the apex. Numerous secondary veins are given off at right angles from a broad midrib: the lateral veins may be simple or forked close to their origin, near the margin, or in the intermediate portion, of the lamina.

It is exceedingly difficult to use Taeniopteris leaves of this form as evidence in regard to the Jurassic or Rhaetic age of plant-bearing strata. The species T. tenuinervis Brauns, as figured by Schenk[1285] from the Rhaetic rocks of Germany and Persia, and recorded from several other regions, presents a close agreement with T. vittata. Oleandridium lentriculiforme Etheridge[1286] from the Hawkesbury series of Australia is another similar leaf. The species T. vittata from the Yorkshire coast, represented in [fig. 332], shows a well-preserved petiole with a clean-cut base like that of the petioles of Oleandra neriiformis and other recent ferns which are detached from the rhizome by the action of an absciss-layer.

Fig. 332. Taeniopteris vittata. (British Museum No. 39217. ⅔ nat. size.)

A broader form of frond with similar venation was described by Lindley and Hutton[1287] as Taeniopteris major. An examination of the type-specimen from the Inferior Oolite of Yorkshire, now in the Manchester Museum, led me to doubt the necessity of specific separation from T. vittata[1288].

A smaller frond of the same general type as T. vittata is recorded from Wealden strata of North Germany and England under the name T. Beyrichii[1289].