Certain species of Pecopteris fronds from Carboniferous strata are characterised by circular sori or synangia consisting of a small number (3–8) of exannulate sporangia attached to a central receptacle and free only at their apices. Strasburger[997] suggested a Marattiaceous affinity for Asterotheca and Stur[998] describes the species Asterotheca Sternbergii Goepp. ([fig. 291], C, D) as an example of a Marattiaceous fern. The latter author retains Corda’s genus Hawlea[999] for the fertile fronds of the common Coal-Measures species Pecopteris Miltoni, while on the other hand Kidston[1000] includes this type in Asterotheca.
Pecopteris (Asterotheca) Miltoni (Artis).
| 1825. | Filicites Miltoni, Artis, Antedil. Phyt. Pl. XIV. |
| 1828. | Pecopteris Miltoni, Brongniart, Prodrome, p. 58. |
| 1828. | Pecopteris abbreviata, Brongniart, Hist. vég. foss. p. 337, Pl. CXV. figs. 1–4; Lindley and Hutton, Foss. Flor. Vol. III. Pl. 184. |
| 1845. | Hawlea pulcherrima, Corda, Flor. Vorwelt, p. 90, Pl. LVII. figs. 7, 8. |
| 1877–1888. | Hawlea Miltoni, Stur, Culm Flora, p. 293; Farne Carbon. Flora, p. 108, Pls. LIX. LX. |
| 1888. | Pecopteris (Asterotheca) abbreviata, Zeiller, Flor. Valenc. p. 186, Pl. XXIV. figs. 1–4. |
Fig. 290.
- Alethopteris lonchitica. × 2½. | For description
- Lonchopteris rugosa. × 2.| see; Chap. XXVII.
- Sphenopteris Hoeninghausi. × 4.|
- Parapecopteris neuropteroides.
- Pecopteris (Dactylotheca) plumosa [= P. (Dactylotheca) dentata Zeiller (88)]. × 4.
(A–C, E, after Zeiller; D, after Grand’Eury.)
The fronds of this species reached a length of more than 3 metres and a breadth of 2 metres. They are characterised by the presence of aphlebiae[1001] appressed to the rachis and by circular sori composed of a small number (3–6) of sporangia. In habit and in the form of the pinnules this type is similar to Dactylotheca plumosa.
Fig. 291.