American Journal of Botany

The American Journal of Botany is a monthly peer-reviewed scientific journal which covers all aspects of plant biology. It has been published by the Botanical Society of America since 1914. According to the Journal Citation Reports, the journal has a 2012 impact factor of 2.586.[1] Access is available through JSTOR with a moving wall of 5 years.

American Journal of Botany
American Journal of Botany
Edited byJudy Jernstedt
Publication details
Publication history
Standard abbreviations
Am. J. Bot.
ISSN0002-9122 (print)
1537-2197 (web)
OCLC no.475054649


  1. ^ "American Journal of Botany". 2012 Journal Citation Reports. Web of Science (Science ed.). Thomson Reuters. 2013.

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Altingiaceae is a small family of flowering plants in the order Saxifragales, and are wind-pollinated trees that produce hard, woody fruits containing numerous seeds. The fruits have been studied in considerable detail. They naturally occur in Central America, Mexico, eastern North America, the eastern Mediterranean, China, and tropical Asia. They are often cultivated as ornamentals and many produce valuable wood.


The Bromeliaceae (the bromeliads) are a family of monocot flowering plants of 51 genera and around 3475 known species native mainly to the tropical Americas, with a few species found in the American subtropics and one in tropical west Africa, Pitcairnia feliciana.They are among the basal families within the Poales and are the only family within the order that has septal nectaries and inferior ovaries. These inferior ovaries characterize the Bromelioideae, a subfamily of the Bromeliaceae. The family includes both epiphytes, such as Spanish moss (Tillandsia usneoides), and terrestrial species, such as the pineapple (Ananas comosus). Many bromeliads are able to store water in a structure formed by their tightly-overlapping leaf bases. However, the family is diverse enough to include the tank bromeliads, grey-leaved epiphyte Tillandsia species that gather water only from leaf structures called trichomes, and a large number of desert-dwelling succulents.

The largest bromeliad is Puya raimondii, which reaches 3–4 m tall in vegetative growth with a flower spike 9–10 m tall, and the smallest is Spanish moss.


Dioecy (Greek: διοικία "two households"; adjective form: dioecious) is a characteristic of a species, meaning that it has distinct male and female individual organisms. Dioecious reproduction is biparental reproduction. Dioecy is one method that excludes self-fertilization and promotes allogamy (outcrossing), and thus tends to reduce the expression of recessive deleterious mutations present in a population. Flowering plants have several other methods of excluding self-fertilization, called self-incompatibility.

Double fertilization

Double fertilization is a complex fertilization mechanism of flowering plants (angiosperms). This process involves the joining of a female gametophyte (megagametophyte, also called the embryo sac) with two male gametes (sperm). It begins when a pollen grain adheres to the stigma of the carpel, the female reproductive structure of a flower. The pollen grain then takes in moisture and begins to germinate, forming a pollen tube that extends down toward the ovary through the style. The tip of the pollen tube then enters the ovary and penetrates through the micropyle opening in the ovule. The pollen tube proceeds to release the two sperm in the megagametophyte.

The cells of an unfertilized ovule are 8 in number and arranged in the form of 3+2+3 (from top to bottom) i.e 3 antipodal cells, 2 polar central cells, 2 synergids & 1 egg cell. One sperm fertilizes the egg cell and the other sperm combines with the two polar nuclei of the large central cell of the megagametophyte. The haploid sperm and haploid egg combine to form a diploid zygote,the process being called syngamy, while the other sperm and the two haploid polar nuclei of the large central cell of the megagametophyte form a triploid nucleus (triple fusion). Some plants may form polyploid nuclei. The large cell of the gametophyte will then develop into the endosperm, a nutrient-rich tissue which provides nourishment to the developing embryo. The ovary, surrounding the ovules, develops into the fruit, which protects the seeds and may function to disperse them.The two central cell maternal nuclei (polar nuclei) that contribute to the endosperm, arise by mitosis from the same single meiotic product that gave rise to the egg. The maternal contribution to the genetic constitution of the triploid endosperm is double that of the embryo.

In a study conducted in 2008 of the plant Arabidopsis thaliana, the migration of male nuclei inside the female gamete, in fusion with the female nuclei, has been documented for the first time using in vivo imaging. Some of the genes involved in the migration and fusion process have also been determined.Evidence of double fertilization in Gnetales, which are non-flowering seed plants, has been reported.

Frederick Charles Newcombe

Frederick Charles Newcombe (1858-1927) was an American botanist, and the first editor-in-chief of the American Journal of Botany Newcombe was born in Flint, Michigan, May 11, 1858, to parents Thomas and Eliza (Gayton) Newcombe, who had emigrated from England in 1848. His early education was obtained in the public schools of Flint. From 1880 to 1887 he taught in the Michigan School for the Deaf at Flint. In 1887 he entered the University of Michigan, and was graduated Bachelor of Science in 1890. He was immediately appointed Instructor in Botany at the University. The year 1892-1893 was spent at the University of Leipzig, where he received the degree of Doctor of Philosophy at the end of the year. He returned to Ann Arbor to become Acting Assistant Professor of Botany in theUniversity. Two years later he became Assistant Professor of Botany, and in 1897 Junior Professor. In 1905 he was made Professor of Botany.

Newcombe was a fellow of the American Association for the Advancement of Science, of which he was one of the secretaries in 1899; a member of the Botanical Society of America and its 7th president; of the Society for Plant Morphology and Physiology, and its first vice-president in 1901; and of the Michigan Academy of Science. Of the last-named he was secretary in 1894, vice-president from 1894 to 1896, and president in 1903.


The Graphidaceae are a family of funghi in the order Ostropales. The current circumscription of Graphidaceae includes all taxa in the formerly independent families Thelotremataceae, Gomphillaceae, and Asterothyriaceae.

Green algae

The green algae (singular: green alga) are a large, informal grouping of algae consisting of the Chlorophyta and Charophyta/Streptophyta, which are now placed in separate divisions, as well as the potentially more basal Mesostigmatophyceae, Chlorokybophyceae and Spirotaenia.The land plants, or embryophytes, are thought to have emerged from the charophytes. Therefore, cladistically, embryophytes belong to green algae as well. However, because the embryophytes are traditionally classified as neither algae nor green algae, green algae are a paraphyletic group. Since the realization that the embryophytes emerged from within the green algae, some authors are starting to include them. The clade that includes both green algae and embryophytes is monophyletic and is referred to as the clade Viridiplantae and as the kingdom Plantae. The green algae include unicellular and colonial flagellates, most with two flagella per cell, as well as various colonial, coccoid and filamentous forms, and macroscopic, multicellular seaweeds. There are about 8,000 species of green algae. Many species live most of their lives as single cells, while other species form coenobia (colonies), long filaments, or highly differentiated macroscopic seaweeds.

A few other organisms rely on green algae to conduct photosynthesis for them. The chloroplasts in euglenids and chlorarachniophytes were acquired from ingested green algae, and in the latter retain a nucleomorph (vestigial nucleus). Green algae are also found symbiotically in the ciliate Paramecium, and in Hydra viridissima and in flatworms. Some species of green algae, particularly of genera Trebouxia of the class Trebouxiophyceae and Trentepohlia (class Ulvophyceae), can be found in symbiotic associations with fungi to form lichens. In general the fungal species that partner in lichens cannot live on their own, while the algal species is often found living in nature without the fungus. Trentepohlia is a filamentous green alga that can live independently on humid soil, rocks or tree bark or form the photosymbiont in lichens of the family Graphidaceae. Also the macroalga Prasiola calophylla (Trebouxiophyceae) is terrestrial, and

Prasiola crispa, which live in the supralittoral zone, is terrestrial and can in the Antarctic form large carpets on humid soil, especially near bird colonies.


Lactoris fernandeziana is a flowering shrub endemic to the cloud forest of Masatierra — Robinson Crusoe Island, of the Juan Fernández Islands archipelago of Chile.


The Laurales are an order of flowering plants. They are magnoliids, related to the Magnoliales.

The order includes about 2500-2800 species from 85-90 genera, which comprise seven families of trees and shrubs. Most of the species are tropical and subtropical, though a few genera reach the temperate zone. The best known species in this order are those of the Lauraceae (for example bay laurel, cinnamon, avocado, and Sassafras), and the ornamental shrub Calycanthus of the Calycanthaceae.

The earliest lauraceous fossils are from the early Cretaceous. It is possible that the ancient origin of this order is one of the reasons for its highly diverged morphology. Indeed, presently no single morphological property is known, which would unify all the members of Laurales. The presently accepted classification is based on molecular and genetic analysis.

List of extinct plants

The following is a list of extinct plants only.


Maxillarieae is a large and complex tribe of orchids native to South and Central America. Within the tribe there are eight subtribes one of which is that of the genus Maxillaria.

Tribe Maxillarieae contains 70 to 80 genera with about 1,000 species; most grow in tropical America as terrestrials or epiphytes, a few are myco-heterotrophs (formerly called saprophytes). Most show pseudobulbs, but a few have reedlike stems or thick underground stems. Blooms have four pollinia.

Subtribe Corallorhizinae: all epiparasites.

Genera: Aplectrum, Corallorrhiza

Subtribe Zygopetalinae: about 150 species. Most exhibited hybrids are to be found in this subtribe.

Alliance Warrea

Genera: Otostylis, Warrea

Alliance Zygopetalum

Genera: Acacallis, Aganisia, Batemannia, Bollea, Cheiradenia, Chondrorhyncha, Cochleanthes, Colax, Pabstia, Promenaea, Zygopetalum

Alliance Bollea

Genera: Bollea, Chondrorhyncha, Cochleanthes, Huntleya, Kefersteinia, Pescatoria, Stenia

Alliance Vargasiella

Genera: Vargasiella

Unallied Genera within Zygopetalinae

Genera: Benzingia, Chaubardia, Chaubardiella, Dodsonia, Galeottia, Hoehneella, Koellensteinia, Neogardneria, Paradisanthus, Scuticaria, Warreella, Warreopsis, Zygosepalum

Alliance Hybrids (Nothogenerics)

Genera: Aitkenara, Bateostylis, Bollopetalum, Chondrobollea, Cochella, Cochlecaste, Cochlenia, Downsara, Durutyara, Hamelwellsara, Huntleanthes, Kanzerara, Keferanthes, Lancebirkara, Otocolax, Otonisia, Palmerara, Rotorara, Zygocaste, Zygolum, Zygonisia, Zygostylis

Subtribe Bifrenariinae: thin and pleated leaves.

Genera: Bifrenaria, Xylobium

Subtribe Lycastinae: thin and pleated leaves.

Genera: Anguloa, Bifrenaria, Lycaste, Neomoorea, Rudolfiella, Sudamerlycaste Teuscheria, Xylobium

Subtribe Stanhopeinae:

Genera: Acineta, Archivea, Braemia, Cirrhaea, Coryanthes, Embreea, Gongora, Horichia, Houlletia, Jennyella, Kegeliella, Lacaena, Lueddemannia, Paphinia, Polycycnis, Schlimmia, Sievekingia, Soterosanthus, Stanhopea, Trevoria, Vasqueziella

Subtribe Coeliopsidinae:

Genera: Coeliopsis, Lycomormium, Peristeria

Subtribe Maxillariinae: largest subtribe with nearly half of the tribe species. The leathery leaves are conduplicate, i.e. folded together lengthwise.

Genera: Chrysocycnis, Cyrtidium, Maxillaria, Mormolyca, Pityphyllum, Scuticaria (plant), Sepalosaccus, Trigonidium

Subtribe Dichaeinae

Genera: Dichaea

Subtribe Telipogoninae

Genera: Telipogon, Trichoceros

Subtribe Ornithocephalinae

Genera: Ornithocephalus, Zygostates


Petals are modified leaves that surround the reproductive parts of flowers. They are often brightly colored or unusually shaped to attract pollinators. Together, all of the petals of a flower are called a corolla. Petals are usually accompanied by another set of special leaves called sepals, that collectively form the calyx and lie just beneath the corolla. The calyx and the corolla together make up the perianth. When the petals and sepals of a flower are difficult to distinguish, they are collectively called tepals. Examples of plants in which the term tepal is appropriate include genera such as Aloe and Tulipa. Conversely, genera such as Rosa and Phaseolus have well-distinguished sepals and petals. When the undifferentiated tepals resemble petals, they are referred to as "petaloid", as in petaloid monocots, orders of monocots with brightly coloured tepals. Since they include Liliales, an alternative name is lilioid monocots.

Although petals are usually the most conspicuous parts of animal-pollinated flowers, wind-pollinated species, such as the grasses, either have very small petals or lack them entirely.


Phyllanthaceae is a family of flowering plants in the eudicot order Malpighiales. It is most closely related to the family Picrodendraceae.The Phyllanthaceae are most numerous in the tropics, with many in the south temperate zone, and a few ranging as far north as the middle of the north temperate zone.Some species of Andrachne, Antidesma, Margaritaria, and Phyllanthus are in cultivation. A few species of Antidesma, Baccaurea, Phyllanthus, and Uapaca bear edible fruit.Phyllanthaceae comprises about 2000 species. Depending on the author, these are grouped into 54 to 60 genera. Some of the genera are poorly defined, and the number of genera in the family is likely to change as the classification is further refined. The genus Phyllanthus, one of the largest genera of flowering plants, with over 1200 species, has more than half of the species in the family.Some of the genera have recently been sunk into others, while other genera have recently been divided. The largest genera and the approximate number of species in each are: Phyllanthus (1270), Cleistanthus (140), Antidesma (100), Aporosa (90), Uapaca (60), Baccaurea (50), and Bridelia (50).Since Phyllanthaceae was revised in 2006, one paper has removed Heterosavia from Savia. Another has separated Notoleptopus from Leptopus, and segregated Pseudophyllanthus and Phyllanthopsis from Andrachne. Also, Oreoporanthera has been subsumed into Poranthera, while Zimmermannia and Zimmermanniopsis have been sunk into Meineckia. The large genus Cleistanthus is known to be polyphyletic, but further studies will be needed before it can be revised.


The Saxifragales are an order of flowering plants. Their closest relatives are a large eudicot group known as the rosids by the definition of rosids given in the APG II classification system. Some authors define the rosids more widely, including Saxifragales as their most basal group. Saxifragales is one of the eight groups that compose the core eudicots. The others are Gunnerales, Dilleniaceae, Rosids, Santalales, Berberidopsidales, Caryophyllales, and Asterids.Saxifragales have an extensive fossil record. The extant members are apparently remnants of a formerly diverse and widespread order.The Saxifragales order, as it is now understood, is based upon the results of molecular phylogenetic studies of DNA sequences. It is not part of any of the classification systems based on plant morphology. The group is much in need of comparative anatomical study, especially in light of the recent expansion of the family Peridiscaceae to include Medusandra, a genus that before 2009 had usually not been placed in Saxifragales.The order is divided into suprafamilial groups as shown on the phylogenetic tree below. These groups are informal and are not understood to have any particular taxonomic rank.


Shorea is a genus of about 196 species of mainly rainforest trees in the family Dipterocarpaceae. The genus is named after Sir John Shore, the Governor-General of the British East India Company, 1793–1798. The timber of trees of the genus is sold under the common names lauan, luan, lawaan, meranti, seraya, balau, bangkirai and Philippine mahogany.


The spermatophytes, also known as phanerogams (taxon Phanerogamae) or phaenogams (taxon Phaenogamae), comprise those plants that produce seeds, hence the alternative name seed plants. They are a subset of the embryophytes or land plants. The term phanerogams or phanerogamae is derived from the Greek φανερός, phanerós meaning "visible", in contrast to the cryptogamae from Greek κρυπτός kryptós = "hidden" together with the suffix γαμέω, gameein, "to marry". These terms distinguished those plants with hidden sexual organs (cryptogamae) from those with visible sexual organs (phanerogamae).


A subshrub (Latin suffrutex) or dwarf shrub is a short woody plant. Prostrate shrub is a related term. "Subshrub" is often used interchangeably with "bush".Because the criteria are matters of degree rather than of kind, the definition of a subshrub is not sharply distinguishable from that of a shrub; examples of reasons for describing plants as subshrubs include ground-hugging stems or low growth habit. Subshrubs may be largely herbaceous, with overwintering perennial woody growth much lower-growing than deciduous summer growth. Some plants described as subshrubs are only weakly woody and some persist for only for a few years; others however, such as Oldenburgia paradoxa live indefinitely, rooted in rocky cracks.

Small, low shrubs such as lavender, periwinkle, and thyme, and many members of the family Ericaceae, such as cranberries and small species of Erica, are often classed as subshrubs.


The Vandeae is a large monophyletic tribe within the family of orchids.

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