Nageia
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Nageia is a genus of conifers belonging to the podocarp family Podocarpaceae.<ref name="pagepodocarpaceae">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. Template:ISBN</ref> Nageia includes evergreen shrubs and trees, from one to 54 meters in height. A 2009 treatment of the genus recognized five species.<ref name="eckenwalder2009">James E. Eckenwalder. 2009. Conifers of the World. Timber Press: Portland, OR, USA. Template:ISBN.</ref> 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.
Description
Nageia are evergreen woody plants that usually grow as trees but may also rarely be shrubs, varying in height from one to 54 meters.<ref name=earle>Template:Cite web</ref> The branching is irregular.<ref name=farjon>Template:Cite book</ref> The thin and hard bark often peels with scale-like plates.<ref name=farjon/>
The leaves are simple and flat. The phyllotaxis or leaf arrangement can be spiral or subopposite and nearly decussate.<ref name=farjon/><ref name=foc>Template:Cite web</ref> The leaf petioles are frequently twisted so the leaves form a flat plane around the shoot.<ref name=earle/><ref name=farjon/> The leaf blade is elliptic, ovate-elliptic or lanceolate in shape.<ref name=earle/><ref name=farjon/> Juvenile leaves are similar in shape to the adult leaves but may be larger or smaller depending on the species.<ref name=foc/> 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.<ref name=farjon/>
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.<ref name=farjon/><ref name=foc/>
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.<ref name=farjon/><ref name=foc/> 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.<ref name=farjon/>
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.<ref name=farjon/> Depending on the species, as the cone matures, the sterile scales may fuse and become fleshy as in the closely related Podocarpus or they may wither.<ref name=farjon/><ref name=foc/> A part of the cone scale supporting the ovule develops into a drupe-like fleshy covering known as the epimatium.<ref name=earle/><ref name=farjon/> The fleshy parts of the cones attract birds, which then disperse the seeds in their droppings.<ref>Flora of China Vol. 4 Page 79 竹柏属 zhu bai shu Nageia Gaertner, Fruct. Sem. Pl. 1: 191. 1788. </ref>
The species of Nageia are distinguished from similar Podocarpus and the other genera in the Podocarpaceae by their broad, flat subopposite leaves with no midrib, superficially similar to those of the unrelated Agathis (Araucariaceae). Nageia is the only genus in Podocarpaceae with multi-veined leaves.
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Broad leaves of N. wallichiana.
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A pair of male cones of N. nagi.
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Female cones of N. nagi with a brown epimatium around the seed.
Distribution
Nageia can be found in the tropical and subtropical moist broadleaf forests of Asia and Australasia, from Assam in eastern India across Southeast Asia to southern China and southern Japan, and across Malesia, from the Malay Peninsula across Indonesia to New Guinea and New Britain.<ref name=u/> An outpost of N. wallichiana is found in the South Western Ghats montane rain forests of southern India, where it is thought to be a relatively recent colonist in biogeographical terms.
Nageia, like many podocarps, can usually be found scattered throughout the forest mixed with other trees, and is rarely if ever found growing in pure stands. The wood is yellowish, typical of podocarps, and a few species are locally important for lumber.
The oldest fossils assigned to the genus are known from the Early Cretaceous of Japan, China and Russia. Other fossils are known from the Eocene of China.<ref>Template:Cite journal</ref><ref>Template:Cite journal</ref>
Classification
The genus contains six species:<ref name=u/><ref name=farjon/>
| Image | Scientific name | Distribution |
|---|---|---|
| File:Nageia fleuryi - 長葉竹柏.jpg | Nageia fleuryi | S China, E Indochina |
| Nageia formosensis | Taiwan | |
| Nageia maxima | Sarawak | |
| Nageia motleyi | S Thailand, W Malaysia, Borneo, Sumatra | |
| File:Nageia nagi kz5.jpg | Nageia nagi | S China (incl. Hainan), Kyushu in Japan, Taiwan |
| File:Gardenology.org-IMG 8126 qsbg11mar.jpg | Nageia wallichiana | SW India; widespread from Assam + Yunnan to Maluku |
- formerly included<ref name=u/>
moved to other genera: Acmopyle Afrocarpus Amentotaxus Cephalotaxus Dacrycarpus Dacrydium Falcatifolium Madhuca Parasitaxus Podocarpus Prumnopitys Putranjiva (Putranjivaceae) Retrophyllum Sundacarpus Template:Columns-list