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Stangeria
Stangeria eriopus is a cycad endemic to southern Africa. It is the sole species in the genus Stangeria.
Stangeria eriopus is a very long-lived, perennial, evergreen cycad. The stalked, feathered, fern-like leaves are between 25 centimeters and two meters long, with the petiole comprising one third to one half of the overall length (in both varieties). They are pinnately-veined, which distinguishes the species from all other cycads. The petiole comprises half the length of the leaf. The young leaves are bent in bud position, the tip appears rolled up. Young leaves are dotted with short, gray hairs (trichomes), which usually fall off quickly and only stick to the petiole. These trichomes are unbranched and transparent or colored. The species occurs as two variable forms or varieties. The forest form, growing in regions with higher rainfall, is characterized by large, wide leaves that can reach up to 2 m in length. The grassland form, growing in regions subject to annual fire and drought, has shorter leaves with a thicker cuticle that may only be 30 cm long.
Stems are completely subterranean and the root tuber is shaped like a carrot, which reaches a diameter of 10 to 25 centimeters. The tip bifurcates into several shoot tips. These form at the beginning wooly scales, but fall off early. As in other cycads, S. eriopus forms coralloid roots. These are specialized, plagiotropic (sideways-growing) roots housing colonies of cyanobacteria Bacillus radicola and Azotobacter sp. that fix nitrogen, much like the roots of legumes.
The tuber is rich in carbohydrates and contains an exceptionally high concentration of sodium sulfate, which explains the breaking-irritant effect. The most common biflavones in the leaves are amentoflavone and bilobetin.
S. eriopus reaches maturity at 5–7 years of age, and has stalked cones as reproductive organs. As is typical of cycads, the species is dioecious, meaning that male and female cones are borne on different plants. Both male and female cones are pedunculated and covered with silvery hair when young, which is deciduous at maturity.
The male cone is cylindrical and tapers towards the tip. At maturity reaches a diameter between 30 – 40 mm and becomes between 10 – 25 cm long. The cone then turns yellowish brown at maturity. The scales or microsporophyll, are arranged cylindrically around the pin axis. Their shape is triangular to rhomboid. Each microsporophyll forms about 150 pollen sacs, which are attached in groups of 3-6 at the bottom. At maturity, the pin axis extends and the scales are lifted apart and release the pollen.
The female cones are ellipsoidal to conical with a rounded tip. The cones are about 18 inches long and reach a diameter of about 8 centimeters. At maturity, the cone turn to dark green. Like the male microsporophylls, the female megasporophylls are cylindrically arranged around the axis. Their tips form but six vertical lines. The ovules are formed at the base of megasporophyll and reach a size of 35 × 25 millimeters. When the cone is ripe, the megasporophylls separate. The micropyle exudes a drop of liquid that pulls the pollen capillary to the embryo sack when it dries. After ripening the seeds, the female cones dissolve and the seeds fall to the ground. They consist of a hard, dark red part, which is surrounded by a fleshy, purple seed coat, which later turns brown. They are about 2 inches long and about 14 millimeters wide.
The cones are insect-pollinated, giving off a faint odor to attract beetle pollinators. At maturity they fall apart to reveal the seeds, which are 2–3 cm in length. The pollen carry on the outside a glycocalyx, which consists of densely packed cylindrical units measuring 20 to 150 nanometers. They are perpendicular to the plasma membrane. Below is the sporopollenin. The germinal openings (apertures) are more proximal than distal. At the distal end of each pollen grain, there is an unusual pit (pseudosulcus) that resembles a "failed" distal aperture.
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Stangeria
Stangeria eriopus is a cycad endemic to southern Africa. It is the sole species in the genus Stangeria.
Stangeria eriopus is a very long-lived, perennial, evergreen cycad. The stalked, feathered, fern-like leaves are between 25 centimeters and two meters long, with the petiole comprising one third to one half of the overall length (in both varieties). They are pinnately-veined, which distinguishes the species from all other cycads. The petiole comprises half the length of the leaf. The young leaves are bent in bud position, the tip appears rolled up. Young leaves are dotted with short, gray hairs (trichomes), which usually fall off quickly and only stick to the petiole. These trichomes are unbranched and transparent or colored. The species occurs as two variable forms or varieties. The forest form, growing in regions with higher rainfall, is characterized by large, wide leaves that can reach up to 2 m in length. The grassland form, growing in regions subject to annual fire and drought, has shorter leaves with a thicker cuticle that may only be 30 cm long.
Stems are completely subterranean and the root tuber is shaped like a carrot, which reaches a diameter of 10 to 25 centimeters. The tip bifurcates into several shoot tips. These form at the beginning wooly scales, but fall off early. As in other cycads, S. eriopus forms coralloid roots. These are specialized, plagiotropic (sideways-growing) roots housing colonies of cyanobacteria Bacillus radicola and Azotobacter sp. that fix nitrogen, much like the roots of legumes.
The tuber is rich in carbohydrates and contains an exceptionally high concentration of sodium sulfate, which explains the breaking-irritant effect. The most common biflavones in the leaves are amentoflavone and bilobetin.
S. eriopus reaches maturity at 5–7 years of age, and has stalked cones as reproductive organs. As is typical of cycads, the species is dioecious, meaning that male and female cones are borne on different plants. Both male and female cones are pedunculated and covered with silvery hair when young, which is deciduous at maturity.
The male cone is cylindrical and tapers towards the tip. At maturity reaches a diameter between 30 – 40 mm and becomes between 10 – 25 cm long. The cone then turns yellowish brown at maturity. The scales or microsporophyll, are arranged cylindrically around the pin axis. Their shape is triangular to rhomboid. Each microsporophyll forms about 150 pollen sacs, which are attached in groups of 3-6 at the bottom. At maturity, the pin axis extends and the scales are lifted apart and release the pollen.
The female cones are ellipsoidal to conical with a rounded tip. The cones are about 18 inches long and reach a diameter of about 8 centimeters. At maturity, the cone turn to dark green. Like the male microsporophylls, the female megasporophylls are cylindrically arranged around the axis. Their tips form but six vertical lines. The ovules are formed at the base of megasporophyll and reach a size of 35 × 25 millimeters. When the cone is ripe, the megasporophylls separate. The micropyle exudes a drop of liquid that pulls the pollen capillary to the embryo sack when it dries. After ripening the seeds, the female cones dissolve and the seeds fall to the ground. They consist of a hard, dark red part, which is surrounded by a fleshy, purple seed coat, which later turns brown. They are about 2 inches long and about 14 millimeters wide.
The cones are insect-pollinated, giving off a faint odor to attract beetle pollinators. At maturity they fall apart to reveal the seeds, which are 2–3 cm in length. The pollen carry on the outside a glycocalyx, which consists of densely packed cylindrical units measuring 20 to 150 nanometers. They are perpendicular to the plasma membrane. Below is the sporopollenin. The germinal openings (apertures) are more proximal than distal. At the distal end of each pollen grain, there is an unusual pit (pseudosulcus) that resembles a "failed" distal aperture.