Fig. 244. Angiopteris evecta. Transverse section of root, with part of the stele magnified: s, sieve-tubes; p, phloem; px, protoxylem.
Archangiopteris. This monotypic genus, discovered by Mr Henry in South Eastern Yunnan, was described by Christ and Giesenhagen in 1899[751]. The comparatively slender rhizome has a fairly simple vascular system[752]. The simply-pinnate leaves bear pinnules like those of Danaea, but the sori agree with those of Angiopteris except in their greater length and in the larger number of sporangia.
Marattia. This genus, which extends “all round the world within the tropics[753],” includes some species which closely resemble Angiopteris, while others are characterised by more finely divided leaves with smaller ultimate segments. The fleshy stipules occasionally have an irregularly pinnatifid form ([fig. 241], B). The sporangia are represented by oval synangia[754] ([fig. 245], A; the black patches at the ends of the lateral veins) composed of two valves, which on ripening come apart and expose two rows of pores formed by the apical dehiscence of the sporangial compartments ([fig. 245], A′, B). In Marattia Kaulfussii the sori are attached to the lamina by a short stalk ([fig. 245], B, B′) and the leaf bears a close resemblance to those of the Umbelliferous genera Anthriscus and Chaerophyllum. The vascular system is constructed on the same plan as that of Angiopteris but is of simpler form.
Fig. 245.
- A. Marattia fraxinea. A′. A single synangium showing the two valves and pores of the sporangial compartments.
- B, B′. M. Kaulfussii.
- C. Kaulfussia (synangium showing pores of sporangial compartments).
- D, E. Marattiopsis Münsteri.
(C, after Hooker; D, E, after Schimper.)
Danaea. Danaea, represented by about 14 species confined to tropical America, is characterised by simple or simply pinnate leaves with linear segments bearing elongated sori extending from the midrib almost to the margin of the lamina. Each sorus consists of numerous sporangia in two parallel rows united into an oblong mass partially overarched by an indusium ([fig. 242], E, i) which grows up from the leaf between the sori. In the portion of a fertile segment shown in [fig. 242], E, the apical pores are seen at a; and at b, where the roof of the synangium has been removed, the spore-bearing compartments are exposed. The vascular system[755] agrees in general plan with that characteristic of the family.
Kaulfussia. The form of the leaf (Vol. I. p. 97, fig. 22) closely resembles that of the Horse Chestnut; the stem is a creeping dorsiventral rhizome with a vascular system in the form of a “much perforated solenostele[756].” The synangia are circular, with a median depression; each sporangial compartment opens by an apical pore on the sloping sides of the synangial cup ([fig. 245], C)[757].