Retrophyllum

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Retrophyllum
Retrophyllum rospigliosii (Decussocarpus rospigliosii) - Lyman Plant House, Smith College - DSC04249.JPG
Retrophyllum rospigliosii
Scientific classification Red Pencil Icon.png
Kingdom: Plantae
Clade: Tracheophytes
Division: Pinophyta
Class: Pinopsida
Order: Pinales
Family: Podocarpaceae
Genus: Retrophyllum
C.N.Page [1]
Type species
Retrophyllum vitiense

Retrophyllum is a genus of conifers in the family Podocarpaceae. [2] It contains five generally recognized extant species with a disjunct distribution in the Southern Hemisphere, found in Papuasia and also in South America. [1] [3] [4] Retrophyllum are evergreen trees typically occurring in tropical rainforests and cloud forests.

Contents

Etymology

The name Retrophyllum is derived from the Latin retro, meaning "backward" or "reversed", and the Greek phyllos, meaning "leaf". The name refers to the unique phyllotaxis where the adaxial surfaces of the leaves face up on one side of the shoot and down on the other. [1]

Description

Leaves of R. minus showing the phyllotaxis. The leaves have their ventral sides up on the left and dorsal sides up on the right. Retrophyllum minus (Jardin des Plantes Paris) (cropped).JPG
Leaves of R. minus showing the phyllotaxis. The leaves have their ventral sides up on the left and dorsal sides up on the right.

Retrophyllum are evergreen trees. They range in size from dwarfed to very large, [1] reaching heights in excess of 40 and potentially 60 meters. [5] Resin canals are found in both leaves and the seed cones. [1] The bark is usually smooth at first, becoming fissured or flaking with age. [1] [5] [6]

The leaves are generally flat with a decurrent base and a spreading blade, but leading and cone-bearing shoots may also have small appressed scale-like leaves. [1] [5] [6] The base phyllotaxis or leaf arrangement is spiral though the leaves usually form subopposite and nearly decussate pairs. The leaves of a lateral shoot are further twisted at their petioles to form two pectinate rows in a horizontal plane around the shoot. [1] The leaf petioles in Retrophyllum are uniquely twisted on the lateral shoots in opposite directions on each side of a shoot orienting the leaf blades with the adaxial or ventral surface upwards on one side of the shoot and the abaxial or dorsal surface upwards on the opposite side of the shoot. [1] [6] [5] The leaf blade varies in shape from lanceolate to narrowly ovate. The leaves have conspicuous midribs and are amphistomatic with stomata present on both sides. [1]

Retrophyllum are dioecious with male pollen cones and female seed cones on separate individual trees. The male pollen cones may be axillary or terminal and solitary or grouped. They have glabrous peduncles. A pollen cone consists of many spirally arranged microsporophylls each with two pollen sacs producing bisaccate pollen. [1]

The female seed cones develop from axillary buds. They are often solitary but may also be paired. The cones consist of several basal sterile cone scales and a single apical fertile scale. The basal scales are fused. The fertile scale has one seed producing ovule. The single seed of the cone is covered by a modified ovuliferous scale known as the epimatium. The epimatium becomes fleshy and drupe-like at maturity. It varies in shape from elliptic to ovoid or pyriform and may be red, violet or purplish brown in color. [1]

Distribution

Retrophyllum has a naturally disjunct distribution covering the Maluku Islands of Indonesia, New Guinea, New Britain and New Ireland in the Asia-Pacific region, Fiji, New Caledonia and Vanuatu in the Pacific and parts of Brazil, Colombia, Ecuador, Peru and Venezuela in South America. [1] The species Retrophyllum minus occurs in riparian and lacustrine habitats on ultramafic soils in New Caledonia. [7] The other species usually grow in tropical lowland or montane rainforests or cloud forests. [5] [6] [8]

Fossil record

Retrophyllum shoots have a distinctive morphology in which the leaves are in subopposite pairs, [1] and twisted in such a way that the abaxial surface of one leaf is up, and in the other it is down. This feature, added to a distinctive epidermal morphology means that well-preserved specimens can be easily identified in the fossil record. The fossil record shows that Retrophyllum was present in the Cenozoic of Argentina, [9] Australia [10] and New Zealand. [11] [12] It is now extinct in those places.

Taxonomy

R. comptonii is native to New Caledonia. Retrophyllum comptonii 2.jpg
R. comptonii is native to New Caledonia.

In a 2009 book on conifers, Retrophyllum piresii was treated as conspecific with Retrophyllum rospigliosii. The author stated "One specimen from low elevations in Brazil was separated as a distinct species, but it falls well within the range of variation of the species as a whole and is geographically close to some locations in Peru."

Species

There are five generally recognized species. [1] [3]

ImageScientific nameDistribution
Retrophyllum comptonii.jpg Retrophyllum comptonii (J.Buchholz) C.N.Page New Caledonia
Retrophyllum minor (Carr.) C.N.Page (AM AK284978-3).jpg Retrophyllum minus (Carrière) C.N.PagePlaine des Lacs in New Caledonia
Retrophyllum piresii (Silba) C.N.Page Serra dos Pacaás Novos in Rondônia State in W Brazil.
Retrophyllum rospigliosii, Colombia - Alejandro Bayer (2).jpg Retrophyllum rospigliosii (Pilg.) C.N.Page Colombia, Venezuela, Peru, Ecuador, Brazil.
Retrophyllum vitiense (Seem.) C.N.Page Maluku, New Guinea, Fiji, Bismarck Archipelago, Santa Cruz Islands.

Related Research Articles

Pinophyta Division of plants including extinct and current conifers

The Pinophyta, also known as Coniferophyta or Coniferae, or commonly as conifers, are a division of vascular land plants containing a single extant class, Pinopsida. They are cone-bearing seed plants, a subset of gymnosperms. All extant conifers are perennial woody plants with secondary growth. The great majority are trees, though a few are shrubs. Examples include cedars, Douglas firs, cypresses, firs, junipers, kauri, larches, pines, hemlocks, redwoods, spruces, and yews. As of 1998, the division Pinophyta was estimated to contain eight families, 68 genera, and 629 living species.

Gymnosperm Clade of non-flowering, naked-seeded plants

The gymnosperms, also known as Acrogymnospermae, are a group of seed-producing plants that includes conifers, cycads, Ginkgo, and gnetophytes. The term "gymnosperm" comes from the composite word in Greek: γυμνόσπερμος, literally meaning "naked seeds". The name is based on the unenclosed condition of their seeds. The non-encased condition of their seeds contrasts with the seeds and ovules of flowering plants (angiosperms), which are enclosed within an ovary. Gymnosperm seeds develop either on the surface of scales or leaves, which are often modified to form cones, or solitary as in yew, Torreya, Ginkgo.

Pinaceae Family of conifers

The Pinaceae, pine family, are trees or shrubs, including many of the well-known conifers of commercial importance such as cedars, firs, hemlocks, larches, pines and spruces. The family is included in the order Pinales, formerly known as Coniferales. Pinaceae are supported as monophyletic by their protein-type sieve cell plastids, pattern of proembryogeny, and lack of bioflavonoids. They are the largest extant conifer family in species diversity, with between 220 and 250 species in 11 genera, and the second-largest in geographical range, found in most of the Northern Hemisphere, with the majority of the species in temperate climates, but ranging from subarctic to tropical. The family often forms the dominant component of boreal, coastal, and montane forests. One species, Pinus merkusii, grows just south of the equator in Southeast Asia. Major centres of diversity are found in the mountains of southwest China, Mexico, central Japan, and California.

Cupressaceae The cypress family of conifers

Cupressaceae is a conifer family, the cypress family, with worldwide distribution. The family includes 27–30 genera, which include the junipers and redwoods, with about 130–140 species in total. They are monoecious, subdioecious or (rarely) dioecious trees and shrubs up to 116 m (381 ft) tall. The bark of mature trees is commonly orange- to red- brown and of stringy texture, often flaking or peeling in vertical strips, but smooth, scaly or hard and square-cracked in some species.

<i>Tsuga</i> Genus of conifers

Tsuga is a genus of conifers in the subfamily Abietoideae. The common name hemlock is derived from a perceived similarity in the smell of its crushed foliage to that of the unrelated plant poison hemlock. Unlike the latter, Tsuga species are not poisonous.

Podocarpaceae Family of conifers in the family Podocarpaceae

Podocarpaceae is a large family of mainly Southern Hemisphere conifers, comprising about 156 species of evergreen trees and shrubs. It contains 19 genera if Phyllocladus is included and Manoao and Sundacarpus are recognized.

<i>Phyllocladus</i> Genus of plants

Phyllocladus, the celery pines, is a small genus of conifers, now usually treated in the family Podocarpaceae.Species occur mainly in New Zealand, Tasmania, and Malesia in the Southern Hemisphere, though P. hypophyllus ranges into the Philippines, a short way north of the equator.

<i>Podocarpus</i> Genus of conifers in the family Podocarpaceae

Podocarpus is a genus of conifers, the most numerous and widely distributed of the podocarp family, the Podocarpaceae. Podocarpus species are evergreen shrubs or trees, usually from 1 to 25 m tall, known to reach 40 m (130 ft) at times. The cones have two to five fused cone scales, which form a fleshy, berry-like, brightly coloured receptacle at maturity. The fleshy cones attract birds, which then eat the cones and disperse the seeds in their droppings. About 97 to 107 species are placed in the genus depending on the circumscription of the species.

<i>Nageia</i> genus of conifers in the family Podocarpaceae

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.

<i>Afrocarpus</i> Genus of conifers

Afrocarpus is a genus of conifers of the family Podocarpaceae. Two to six species are recognized. They are evergreen trees native to Africa. Afrocarpus was designated a genus in 1989, when several species formerly classified in Podocarpus and Nageia were reclassified.

<i>Athrotaxis</i> Genus of conifers

Athrotaxis is a genus of two to three species of conifers in the cypress family, Cupressaceae. The genus is endemic to western Tasmania, where they grow in high altitude temperate rainforests.

<i>Halocarpus bidwillii</i> Species of conifer

Halocarpus bidwillii, the mountain pine or bog pine, is a species of conifer in the family Podocarpaceae. It is native and endemic to New Zealand.

A strobilus is a structure present on many land plant species consisting of sporangia-bearing structures densely aggregated along a stem. Strobili are often called cones, but some botanists restrict the use of the term cone to the woody seed strobili of conifers. Strobili are characterized by a central axis surrounded by spirally arranged or decussate structures that may be modified leaves or modified stems.

Dacrydium guillauminii, commonly known as cat-tail Rimu or swamp Dacrydium, is a species of conifer in the family Podocarpaceae. It is found only in New Caledonia. It is a slow growing shrub or small tree with roots that grow in water, and reaches a height between 1 and 2 metres.

Podocarpus coriaceus, commonly known as the yucca plum pine, is a species of conifer, an evergreen tree in the family Podocarpaceae. It is found in the Dominican Republic, Guadeloupe, Martinique, Montserrat, Puerto Rico, and Saint Kitts and Nevis.

Podocarpus magnifolius is a species of conifer in the family Podocarpaceae. It is found in Bolivia, Colombia, Peru, Panama and Venezuela.

<i>Podocarpus sprucei</i> Species of conifer

Podocarpus sprucei is a species of conifer in the family Podocarpaceae. It is found largely in Ecuador and Peru.

<i>Retrophyllum rospigliosii</i> Species of conifer

Retrophyllum rospigliosii is a species of conifer in the family Podocarpaceae. It is a large evergreen tree native to the montane rainforests of Venezuela, Colombia, Peru, Ecuador and Bolivia in South America.

Retrophyllum vitiense is a species of conifer in the family Podocarpaceae. It is a large evergreen rainforest emergent tree native to Fiji, Indonesia, Papua New Guinea, and Solomon Islands.

<i>Pherosphaera hookeriana</i> Species of conifer

Pherosphaera hookeriana, or Mount Mawson pine, is a dwarf conifer endemic to Tasmania, at altitudes above 600 meters. There are roughly 30 known sites, with population numbers in the tens of thousands. The species occurs in a range of habitats typically in areas near water bodies, mostly on dolerite geology. The species is highly fire sensitive and an increase in fire events associated with climate change may lead to local extinction in some areas and fragmentation of habitat

References

  1. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Farjon, Aljos (2010). A Handbook of the World's Conifers. Leiden: Brill. p. 937. ISBN   9789004177185.
  2. 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. ISBN   978-0-387-51794-0
  3. 1 2 Kew World Checklist of Selected Plant Families
  4. James E. Eckenwalder. 2009. Conifers of the World. Timber Press: Portland, OR, USA. ISBN   978-0-88192-974-4.
  5. 1 2 3 4 5 Farjon, Aljos (2010). A Handbook of the World's Conifers. p. 942.
  6. 1 2 3 4 Farjon, Aljos (2010). A Handbook of the World's Conifers. p. 941.
  7. Farjon, Aljos (2010). A Handbook of the World's Conifers. p. 938.
  8. Farjon, Aljos (2010). A Handbook of the World's Conifers. p. 943.
  9. Wilf, P.; Johnson, K.R.; Cúneo, N.R.; Smith, M.E.; Singer, B.S.; Gandolfo, M.A. (2005). "Eocene Plant Diversity at Laguna del Hunco and Río Pichileufú, Patagonia, Argentina". The American Naturalist . 165 (6): 634–650. doi:10.1086/430055. PMID   15937744 . Retrieved 2019-02-22.
  10. Hill, R.S. and Pole, M.S., 1992. Leaf and Shoot Morphology of Extant Afrocarpus, Nageia and Retrophyllum (Podocarpaceae) Species, and Species with similar Leaf Arrangement from Tertiary sediments in Australasia. Australian Systematic Botany.
  11. Pole, M.S., 1992. Early Miocene flora of the Manuherikia Group, New Zealand. 2. Conifer. Journal of the Royal Society of New Zealand, 22: 287-302.
  12. Pole, M.S., 1997. Miocene conifers from the Manuherikia Group, New Zealand. Journal of the Royal Society of New Zealand, 27: 355-370.