Nageia is agenus ofconifers belonging to the podocarp familyPodocarpaceae.[4]Nageia includesevergreenshrubs andtrees, from one to 54 meters in height. A 2009treatment of the genus recognized fivespecies.[5] Some authors considerNageia formosensis to be a separate species fromNageia nagi, thus recognizing six species. The podocarp genera have been reshuffled by various botanists. Most recently, several species formerly classed asNageia were moved to the new genusRetrophyllum, whileNageia falcata andNageia mannii were moved to the new genusAfrocarpus.
Nageia are evergreen woody plants that usually grow as trees but may also rarely be shrubs, varying in height from one to 54 meters.[6] The branching is irregular.[7] The thin and hard bark often peels with scale-like plates.[7]
Theleaves are simple and flat. Thephyllotaxis or leaf arrangement can be spiral or subopposite and nearly decussate.[7][8] The leaf petioles are frequently twisted so the leaves form a flat plane around the shoot.[6][7] The leaf blade is elliptic, ovate-elliptic or lanceolate in shape.[6][7] Juvenile leaves are similar in shape to the adult leaves but may be larger or smaller depending on the species.[8] 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.[7]
Nageia are generallydioecious, with male pollen cones and female seed cones borne on separate individual plants but may sometimes bemonoecious. Thecones are pedunculate and develop fromaxillary buds.[7][8]
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.[7][8] 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 bisaccatepollen.[7]
The seed cones are solitary and have long peduncles. They have several sterile and one or rarely two fertile scales, each fertile scale with oneseed producingovule.[7] Depending on the species, as the cone matures, the sterile scales may fuse and become fleshy as in the closely relatedPodocarpus or they may wither.[7][8] A part of the cone scale supporting the ovule develops into adrupe-like fleshy covering known as the epimatium.[6][7] The fleshy parts of the cones attractbirds, which thendisperse the seeds in their droppings.[9]
The species ofNageia are distinguished from similarPodocarpus and the other genera in the Podocarpaceae by their broad, flat subopposite leaves with nomidrib, superficially similar to those of the unrelatedAgathis (Araucariaceae).Nageia is the only genus in Podocarpaceae with multi-veined leaves.
Nageia, like many podocarps, can usually be found scattered throughout theforest mixed with other trees, and is rarely if ever found growing in purestands. Thewood is yellowish, typical of podocarps, and a few species are locally important forlumber.
The oldest fossils assigned to the genus are known from theEarly Cretaceous of Japan, China and Russia. Other fossils are known from theEocene of China.[10][11]
^illustration from Flora Japonica, Sectio Prima (Tafelband). 1870 by Philipp Franz von Siebold and Joseph Gerhard Zuccarini
^Christopher N. Page. 1990. "Podocarpaceae" pages 332-346. In: Klaus Kubitzki (general editor); Karl U. Kramer and Peter S. Green (volume editors)The Families and Genera of Vascular Plants volume I. Springer-Verlag: Berlin;Heidelberg, Germany.ISBN978-0-387-51794-0
^James E. Eckenwalder. 2009.Conifers of the World. Timber Press: Portland, OR, USA.ISBN978-0-88192-974-4.
^abcdEarle, Christopher J. (2012)."Nageia".The Gymnosperm Database, conifers.org. RetrievedApril 2, 2016.
^abcde"Nageia".eFloras: Flora of China. Missouri Botanical Garden, St. Louis, MO & Harvard University Herbaria, Cambridge, MA. 1999. RetrievedApril 2, 2016.
