Fagopsis longifolia

Fagopsis is an extinct genus of beech relative in the family Fagaceae with two accepted species – Fagopsis longifolia and Fagopsis undulata. It has been found in fossil strata ranging in age between the Early Eocene to the Late Eocene or Early Oligocene in British Columbia, Colorado, Montana, and Washington. Several other species were formerly placed in the genus, but later removed because of insufficient associated fossils.

Wikipedia-Autoren · CC BY-SA · Quelle

In his brief description of the genus Fagopsis, Hollick defines the leaves as lanceolate to elliptical in outline, with margins that are either regularly dentate or roughly but regularly crenate. The leaves are craspedodromus with secondary veins running straight from the primary veins to the margins, where they often terminate in the teeth. To this, Manchester and Crane noted the tertiary venation is very fine. F. longifolia Fagopsis longifolia branches show monopodial arrangement of the side branches, fruits and leaves. The central axis continues to grow with smaller side branches staying subordinate to the central one. The leaves are up to 14 cm (5.5 in) long and 50 mm (2.0 in) wide, resulting in length to width ratios of 1 to 2 and 1 to 3. They have a petiole that is 12 mm (0.47 in) long and 1.5 mm (0.059 in) wide. The teeth are non-glandular and simple, with a supporting vein terminating in the tooth tip. The secondary veins are sub-opposite to alternate in position on the primary vein. The male pollen cones are spherical in shape, ranging between 8–12 mm (0.31–0.47 in) in diameter, and comprised of numerous flowering heads. The cones develop on peduncles which reach up to 6 mm (0.24 in) in length by 2 mm (0.079 in) wide. Each flower has a filament and two basifixed anthers, each with two pollen sacks. On specimens with the cones still attached to branches, the cones are produced on small side branches of the main stem, and no female cones are present. A detailed examination of pollen extracted from fossils was published by Johannes Bouchal et al in 2014. The overall pollen grain architecture is closer to subfamily Castaneoideae genera and not Quercus or Fagus. The pollen grains are produced as monads, with each grain separate from the other, rather than being triads or tetrads with multiple grains fused together. The grains range between spheroids to prolate, lemon-shaped, in outline. Pollen grains in the cones still were measured to have polar diameters between 22 and 27 μm, and an equatorial diameter of 19–21 μm. Loose pollen gains from sediment samples are slightly larger, with diameters of 22–28 μm polar and 19–26 μm equatorial. The grains have a threefold symmetry, being tricolporate and showing three germination furrows which range between 18 and 22 μm in length. The surface has microtexturing expressed as minute ridged textures, microrugulae, which combine into larger ridges which form a vermiculate "can of worms" sculpturing. Unlike the male cones, female cones are ellipsoidal during early growth and pollination stages, with sizes averaging 11 mm (0.43 in) long and 10 mm (0.39 in) wide. The main body is surrounded by elongated filaments that Manchester and Crane deemed styles. The styles are grouped in threes with the tips curving in a slight hook and extend above the surface of the cone between 3–3.5 mm (0.12–0.14 in). After pollination the cones develop into fruiting cones, with an increased mature length between 12–18 mm (0.47–0.71 in) and width between 8–14 mm (0.31–0.55 in). The fruiting head is comprised of approximately 40 "fruit wedges", possibly cupules, which are arranged in a helical pattern on the central axis. The basal and apical fruits appear to have been more firmly attached to the central axis and were frequently not shed when the central fruits were. After shedding fruits, the central axis shows scarring from each fruit shed. The scars are grouped in threes and have an encircling affixed bract. The cupules are a wedge or cone shaped, having a 1 mm (0.039 in) base which flares over 4–6 mm (0.16–0.24 in) length to a 3–5 mm (0.12–0.20 in) wide heads. The head has up to nine minute teeth ringing the upper edge. Each internal side of the fruits appear to have been covered by mats of fine 50+ μm long hairs. The fruits are often divided into two to three sections vial longitudinal creases on the fruit sides. At the base of each fruit section are small fruits with ovoid outlines. The long axis are 0.5–0.7 mm (0.020–0.028 in) and the short sides are 0.3–0.5 mm (0.012–0.020 in). F. undulata Wolfe and Wehr (1987) distinguished F. undulata from F. longifolia by the more rounded crenate teeth with shallower sinuses between each tooth. There are more secondaries and teeth overall then seen in F. longifolia. Wolfe and Wehr noted that F. undulata leaves found at the Resner Canyon and Graphite Creek sites near the Canadian border north of Republic are on average smaller than the Republic specimens. The Republic leaves have an average of 15 secondary vein pair, in contrast to the northern leaves with average secondary pair counts of 10 to 13. A full description of the female cones found associated with the F. undulata leaves at Resner Canyon and Graphite Creek was not provided, but they were noted to be smaller overall then the female cones of F. longifolia.

Wikipedia-Autoren · CC BY-SA · Quelle