Gerrit S. Miller still had in his 1924 edition of List of North American Recent Mammals in the section “ Genus Canis Linnaeas ,” the subordinate heading “ Subgenus Thos Oken ” and backed it up with a reference to Heller.

* Subgenus Lavandula is mainly of woody shrubs with entire leaves.

* Subgenus Rhododendron L .: small leaf or lepidotes ( with scales on the underside of their leaves ); several hundred species, type: Rhododendron ferrugineum.

; Subgenus Oxycoccus: The cranberries, with slender, trailing, wiry non-woody shoots and strongly reflexed flower petals.

; Subgenus Vaccinium: All the other species, with thicker, upright woody shoots and bell-shaped flowers.

* Subgenus Pinus Scale with a sealing band.

Subgenus Stethomyia is an outlier with respect to these two taxa.

* Subgenus Rhamnus: flowers with four petals, buds with bud scales, leaves opposite or alternate, branches with spines.

* Subgenus Frangula: flowers with five petals, buds without bud scales, leaves always alternate, branches without spines.

* Subgenus Hymenanthes ( Blume ) K. Koch: large leaf or elepidotes ( without scales on the underside of their leaves ); about 140 species, type: Rhododendron degronianum.

* Subgenus Pentanthera G. Don: deciduous azaleas ; about 25 species, type Rhododendron luteum.

* Subgenus Tsutsusi: evergreen azaleas, about 110 species ; type Rhododendron indicum.

* Subgenus Cucullatia: (≡ Megema ) 4 species – M. cerastes, M. corniculata, M. cucullata, M. macrura

* Subgenus Fissia: (≡ Fissia ) 3 species – M. mutica, M. picturata, M. pleurothalloides

* Subgenus Sabaudia constitutes two species in the southwest Arabian peninsula and Eritrea, which are rather distinct from the other species, and are sometimes placed in their own genus Sabaudia.

* Subgenus Candidastrum ( Sleumer ) Philipson & Philipson: one species ; Rhododendron albiflorum.

* Subgenus Mumeazalea: one species, Rhododendron semibarbatum.

* Subgenus Therorhodion: one species, Rhododendron camtschaticum.

* Subgenus Meleagris: (≡ Rodrigoa ) 7 species, e. g. M. anisomorpha, M. heteroptera, M. meleagris

* Subgenus Nidifica: (≡ Buccella ) 4-5 species: e. g. M. dynastes, M. nidifica ( including M. ventricosa )

* Subgenus Dracula: This subgenus contains all the species of the genus except two exceptional species ( D. sodiroi and D. xenos )

Subgenus Nyssorhynchus has been divided in three sections: Albimanus ( 19 species ), Argyritarsis ( 11 species ) and Myzorhynchella ( 4 species ).

* Trees: such as pine ( Pinus ), birch ( Betula ), alder ( Alnus ), cedar, hazel, hornbeam ( Carpinus ), horse chestnut ( Aesculus ), willow ( Salix ), poplar, plane ( Platanus ), linden / lime ( Tilia ) and olive ( Olea ).

Trees in the Arboretum include: Acacia dealbata, Acer campestre, Acer negundo, Acer paxii, Acer saccharinum, Aesculus x carnea, Agathis robusta, Alnus rhombifolia, Angophora costata, Araucaria bidwillii, Archontophoenix cunninghamiana, Baphia chrysophylla, Bauhinia forficata, Bauhinia variegata, Betula nigra, Brachychiton acerifolius, Brachychiton acerifolius ( Herman hybrid ), Brachychiton discolor, Brachychiton populneus, Brahea armata, Brahea brandegeei, Brahea edulis, Butia capitata, Calocedrus decurrens, Calodendrum capense, Caryota urens, Castanospermum australe, Casuarina cunninghamiana, Cedrus deodara, Cedrus libani, Celtis australis, Chamaerops humilis, Chionanthus retusus, Chorisia insignis, Chorisia speciosa, Cryptocarya rubra, Cryptomeria japonica, Cupaniopsis anacardioides, Cupressus glabra, Cupressus sp., Dalbergia sissoo, Dracaena draco, Ehretia anacua, Ehretia tinifolia, Eriobotrya deflexa, Eriobotrya japonica, Erythrina coralloides, Erythrina falcata, Erythrina humeana, Eucalyptus camaldulensis, Eucalyptus citriodora, Eucalyptus cladocalyx, Eucalyptus globulus, Eucalyptus robusta, Eucalyptus rudis, Eucalyptus viminalis, Ficus microcarpa nitida, Ficus racemosa, Ficus religiosa, Ficus sp., Fraxinus uhdei, Fraxinus velutina, Heteromeles arbutifolia, Jacaranda acutifolia, Jubaea chilensis, Juglans nigra, Lagerstroemia indica, Liquidambar formosana, Liriodendron tulipifera, Livistona australis, Livistona chinensis, Macadamia ternifolia, Magnolia grandiflora, Metasequoia glyptostroboides, Metrosideros excelsa, Myrcia cauliflora, Nyssa sylvatica, Phoenix canariensis, Phoenix dactylifera, Phoenix reclinata, Phoenix reclinata ( hybrid ), Phoenix roebelenii x rupicola, Phoenix rupicola, Phytolacca dioica, Pinus canariensis, Pinus edulis, Pinus halepensis, Pinus thunbergii, Pittosporum phillyraeoides, Pittosporum tenuifolium, Pittosporum undulatum, Podocarpus gracilior, Podocarpus totara, Psidium guajava, Quercus agrifolia, Quercus alba, Quercus cerris, Quercus coccinea, Quercus macrocarpa, Quercus palustris, Quercus rubra, Quercus suber, Quercus virginiana, Rhapidophyllum hystrix, Rhapis excelsa, Rhodosphaera rhodanthema, Rhopalostylis baueri, Rhus integrifolia, Sabal causiarum, Sabal sp., Salix babylonica, Schinus molle, Schinus polygamus, Sequoiadendron giganteum, Syagrus romanzoffiana, Tabebuia avellanedae, Taxodium distichum, Tipuana tipu, Toona ciliata, Trachycarpus fortunei, Trachycarpus wagnerianus, Tristania laurina, Trithrinax acanthocoma, Ulmus americana, Umbellularia californica, Washingtonia filifera, Washingtonia robusta, and Zelkova serrata.

In the fall the forests become brilliant with color from Andean Alder ( Alnus acuminata ) and poplar ( Populus spp.

Interplanting walnut plantations with a nitrogen fixing plant, such as Elaeagnus × ebbingei or Elaeagnus umbellata, and various Alnus species, results in a 30 % increase in tree height and girth ( Hemery 2001 ).

Alder bark ( Alnus glutinosa ) with characteristic lenticels and abnormal lenticels on callused areas.

Alnus glutinosa is most noted for the symbiotic relationship with the bacterium Frankia alni, which forms nodules on the tree's roots.

The Colchian rain forests are mixed, with deciduous Black Alder ( Alnus glutinosa ), hornbeam ( Carpinus betulus and C. orientalis ), Oriental Beech ( Fagus orientalis ), and Sweet Chestnut ( Castanea sativa ) together with evergreen Nordmann Fir ( Abies nordmanniana, the tallest tree in Europe at 78m ), Caucasian Spruce ( Picea orientalis ) and Scots Pine ( Pinus sylvestris ).

He also reported having found in a frozen, sandy clay layer and lying on its side, a complete tree of Alnus fruticosa 15 to 20 ft ( 4. 5 to 6 m ) in length, including roots, with leaves and cones adhering.

Root nodules that occur on non-legume genera like Parasponia in association with Rhizobium bacteria, and those that arise from symbiotic interactions with Actinobacteria Frankia in some plant genera such as Alnus, vary significantly from those formed in the legume-rhizobia symbiosis.

It is generally found with oak ( Quercus ), birch ( Betula ), spruce ( Picea ), pine ( Pinus ), chestnut ( Castanea ) and alder ( Alnus ), with which it forms mycorrhizae.

Alnus incana ( Grey Alder or Speckled Alder ) is a species of alder with a wide range across the cooler parts of the Northern Hemisphere.

; Alnus nepalensis forests ; Schima wallichii-Castanopsis indica hygrophile forest ; Schima-Pinus forest ; Pinus roxburghii forests with Phyllanthus emblica.

The stream is bordered for most of its length by Alder Alnus glutinosa, with a ground flora dominated by Ramsons Allium ursinum.

Middle elevations are predominantly forests of Maritime Pine ( Pinus pinaster ) interspersed with forests of mixed broadleaf deciduous trees, including Downy oak ( Q. pubescens ), Sessile Oak ( Q. petraea ), European Hop-Hornbeam ( Ostrya carpinifolia ), Italian Alder ( Alnus cordata ) and Sweet Chestnut ( Castanea sativa ).

The highest elevations are subalpine shrublands, with Green Alder ( Alnus viridis ) juniper ( Juniperus communis subsp.

They differ from the alders ( Alnus, other genus in the family ) in that the female catkins are not woody and disintegrate at maturity, falling apart to release the seeds, unlike the woody, cone-like female alder catkins.

The largest species are red alder ( A. rubra ) on the west coast of North America, and black alder ( A. glutinosa ), native to most of Europe and widely introduced elsewhere, both reaching over 30 m. By contrast, the widespread Alnus viridis ( green alder ) is rarely more than a 5 m tall shrub.

Alnus rubra grows from southeast Alaska south to central coastal California, nearly always within about 200 km of the Pacific coast, except for an extension 600 km inland across northern Washington into northernmost Idaho.

Alnus glutinosa is a tree that thrives in moist soils, and grows under favourable circumstances to a height of 20 – 30 m, exceptionally up to 37 m, though often less.

* Alnus – Alder

* Alnus – Alder

* Alnus – Alder