Paisia E. M. FRIIS, M. M. MENDES et K. R. PEDERSEN 2018
Creators: name: Friis, Else Marie
name: Crane, Peter R.
name: Pedersen, Kaj Raunsgaard
name: Mendes, Mário Miguel
name: Kvaček, Jiří
Publisher: name: Zenodo
Year: 2022
Subjects: Biodiversity
Taxonomy
Plantae
Tracheophyta
Magnoliopsida
Paisia

description: Paisia -like follicles
Text-figs 34a–h, 35a–e, 36a–e
Description and remarks. The material includes several isolated follicles probably derived from apocarpous gynoecia. The follicles vary considerably in size and shape, and range from narrow elongated-ellipsoidal to obovate. Follicles are 0.7–1.7 mm long, 0.35–0.7 mm broad in the dorsi-ventral direction, and 0.3–6.2 mm wide (Textfigs 34a–h, 35a–e, 36a–e).
The follicles have a distinct ventral suture with a decurrent stigma that extends along the full length of the follicle. In some specimens there is a distinct papillate zone that extends along both sides of the ventral suture from the follicle base to the apex (Text-fig. 34a–d). This papillate zone is possibly stigmatic. In many specimens the follicles have a distinct apical cleft (Text-figs 34d, 35a, d, 36b, d).
The follicles contain many anatropous ovules/seeds that are borne on placentae that extend on either side of the ventral suture for the full length of the follicle. In most specimens the ovules/seeds are arranged in two distinct rows (Text-figs 34e–h, 35e), but in one specimen (Text-fig. 36a–e) this is less distinct and the ovules/seeds are more crowded. This specimen is larger than the other follicles and clearly more mature. There are smaller undeveloped ovules in its lower part (Text-fig. 36c) but there are larger, probably mature, seeds in the upper part (Text-fig. 36c). Whether the crowding of the seeds is due to the stage of maturity of the follicles, or because this larger specimen represents another species, is uncertain. The epidermal cells of the ovules/seeds have slightly raised anticlinal walls that give the surface a striate-reticulate appearance (Text-figs 34e, f, 36c).
The follicle wall is thick. It consists of an inner layer of transversely aligned fibres (Text-fig. 34e), a middle layer that is one to two cell layers deep and an outer epidermis of smaller, thin-walled cells (Text-figs 34g, 35e). The mesocarp is composed of large, isodiametric, thick-walled cells that have a rounded cell lumen (Text-figs 34e, f, h, 35e). The follicle is supplied by one dorsal and two ventral bundles (Text-figs 34g, h, 35e, 36e).
Affinity and other occurrences. The follicles are closely similar to the follicles seen in flowers of Paisia pantoporata in their elongate shape and in the anatomical details of the follicle wall. However, the carpels in the Paisia flowers are immature and the stigmatic zone is indistinct. Other features seen in the isolated follicles, such as the apical cleft, and a papillate zone extending along the margins of the ventral suture, are also not seen in Paisia pantoporata. It is possible that the isolated follicles represent different developmental stages of a single species, perhaps Paisia pantoporata. However, it is also possible that they represent additional species of Paisia or a closely related genus.
Isolated follicular fruits occur in other mesofossil floras from Portugal, but Paisia -like follicles like those described here are known only from Catefica.
description: Published as part of Friis, Else Marie, Crane, Peter R., Pedersen, Kaj Raunsgaard, Mendes, Mário Miguel & Kvaček, Jiří, 2022, The Early Cretaceous Mesofossil Flora Of Catefica, Portugal: Angiosperms, pp. 341-424 in Fossil Imprint 78 (2) on pages 388-389, DOI: 10.37520/fi.2022.016, http://zenodo.org/record/7522801