Concept

Nageia

Summary
Nageia is a genus of conifers belonging to the podocarp family Podocarpaceae. Nageia includes evergreen shrubs and trees, from one to 54 meters in height. A 2009 treatment of the genus recognized five species. Some authors consider Nageia formosensis to be a separate species from Nageia nagi, thus recognizing six species. The podocarp genera have been reshuffled by various botanists. Most recently, several species formerly classed as Nageia were moved to the new genus Retrophyllum, while Nageia falcata and Nageia mannii were moved to the new genus Afrocarpus. Nageia are evergreen woody plants that usually grow as trees but may also rarely be shrubs, varying in height from one to 54 meters. The branching is irregular. The thin and hard bark often peels with scale-like plates. The leaves are simple and flat. The phyllotaxis or leaf arrangement can be spiral or subopposite and nearly decussate. The leaf petioles are frequently twisted so the leaves form a flat plane around the shoot. The leaf blade is elliptic, ovate-elliptic or lanceolate in shape. Juvenile leaves are similar in shape to the adult leaves but may be larger or smaller depending on the species. The leaves have multiple parallel longitudinal veins converging toward the ends. Stomata may be found on either both surfaces of the leaf or only the abaxial or underside. The leaf surface is coriaceous. Nageia are generally dioecious, with male pollen cones and female seed cones borne on separate individual plants but may sometimes be monoecious. The cones are pedunculate and develop from axillary buds. The pollen cones are long and ovoid-cylindric in shape. They may be solitary or grow in small spicate groups of two to six cones. Each pollen cone has numerous spirally inserted microsporophylls. The microsprophylls may be triangular or apiculate in shape. Each of them has two basal pollen sacs with bisaccate pollen. The seed cones are solitary and have long peduncles. They have several sterile and one or rarely two fertile scales, each fertile scale with one seed producing ovule.
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