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Used URL style for references. Updated citation for including Cephalotaxus in Taxaceae (Quinn et al. 2002; Rai et al. 2008) and reorganized text on family composition. Removed text on out-of-date Austrotaxaceae speculation
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==Classification==
==Classification==
Taxaceae is now generally included with all other conifers in the order [[Pinales]], as [[DNA]] analysis has shown that the yews are [[monophyletic]] with the other families in the Pinales (Chase ''et al.'', 1993; Price, 2003), a conclusion supported by [[wikt:micromorphology|micromorphology]] studies (Anderson & Owens, 2003). Formerly they were often treated as distinct from other conifers by placing them in a separate order [[Taxales]]. [[Ernest Henry Wilson]] referred to Taxaceae as ''taxad'' in his book ”1916, Conifers and taxads of Japan".<ref>[http://www.britannica.com/#search=tab~TOPICS%2Cterm~TAXAD&tab=active~home%2Citems~home&title=Britannica%20Online%20Encyclopedia taxad (plant family)] : see Taxaceae; [[britannica]]</ref>
Taxaceae is now generally included with all other conifers in the order [[Pinales]], as [[DNA]] analysis has shown that the yews are phylogenetically nested in the Pinales <ref name="Chase Soltis Olmstead Morgan 1993 p=528">{{cite journal | last=Chase | first=Mark W. | last2=Soltis | first2=Douglas E. | last3=Olmstead | first3=Richard G. | last4=Morgan | first4=David | last5=Les | first5=Donald H. | last6=Mishler | first6=Brent D. | last7=Duvall | first7=Melvin R. | last8=Price | first8=Robert A. | last9=Hills | first9=Harold G. | last10=Qiu | first10=Yin-Long | last11=Kron | first11=Kathleen A. | last12=Rettig | first12=Jeffrey H. | last13=Conti | first13=Elena | last14=Palmer | first14=Jeffrey D. | last15=Manhart | first15=James R. | last16=Sytsma | first16=Kenneth J. | last17=Michaels | first17=Helen J. | last18=Kress | first18=W. John | last19=Karol | first19=Kenneth G. | last20=Clark | first20=W. Dennis | last21=Hedren | first21=Mikael | last22=Gaut | first22=Brandon S. | last23=Jansen | first23=Robert K. | last24=Kim | first24=Ki-Joong | last25=Wimpee | first25=Charles F. | last26=Smith | first26=James F. | last27=Furnier | first27=Glenn R. | last28=Strauss | first28=Steven H. | last29=Xiang | first29=Qui-Yun | last30=Plunkett | first30=Gregory M. | last31=Soltis | first31=Pamela S. | last32=Swensen | first32=Susan M. | last33=Williams | first33=Stephen E. | last34=Gadek | first34=Paul A. | last35=Quinn | first35=Christopher J. | last36=Eguiarte | first36=Luis E. | last37=Golenberg | first37=Edward | last38=Learn | first38=Gerald H. | last39=Graham | first39=Sean W. | last40=Barrett | first40=Spencer C. H. | last41=Dayanandan | first41=Selvadurai | last42=Albert | first42=Victor A. | title=Phylogenetics of Seed Plants: An Analysis of Nucleotide Sequences from the Plastid Gene rbcL | journal=Annals of the Missouri Botanical Garden | publisher=JSTOR | volume=80 | issue=3 | year=1993 | issn=0026-6493 | doi=10.2307/2399846 | page=528}}</ref>, a conclusion supported by [[wikt:micromorphology|micromorphology]] studies <ref name="Anderson Owens 2003 pp. 233–234">{{cite journal | last=Anderson | first=E. | last2=Owens | first2=J.N. | title=ANALYZING THE REPRODUCTIVE BIOLOGY OF TAXUS: SHOULD IT BE INCLUDED IN CONIFERALES? | journal=Acta Horticulturae | publisher=International Society for Horticultural Science (ISHS) | issue=615 | year=2003 | issn=0567-7572 | doi=10.17660/actahortic.2003.615.22 | pages=233–234}}</ref>. Formerly they were often treated as distinct from other conifers by placing them in a separate order [[Taxales]]. [[Ernest Henry Wilson]] referred to Taxaceae as taxads in his book ”1916, Conifers and taxads of Japan".<ref>[http://www.britannica.com/#search=tab~TOPICS%2Cterm~TAXAD&tab=active~home%2Citems~home&title=Britannica%20Online%20Encyclopedia taxad (plant family)] : see Taxaceae; [[britannica]]</ref>


''Cephalotaxus'' is now included in Taxaceae, rather than being recognized as the sole genus in its own family, Cephalotaxaceae. The broadly defined Taxaceae (including ''Cephalotaxus'') comprises six extant genera and about 30 species overall.
Some studies in the early 2000s suggested the genera ''Torreya'' and ''Amentotaxus'' were better transferred to [[Cephalotaxaceae]], as genetic tests showed they are more closely related to ''Cephalotaxus'' than to ''Taxus''. More recent studies have included, with ''Cephalotaxus'', in a broader interpretation of Taxaceae as a single larger family (Price, 2003). In this sense, the Taxaceae includes six genera and about 30 species.

Phylogenetic evidence strongly supports a very close relationship between ''Cephalotaxus'' and other members of Taxaceae<ref name="Quinn Price Gadek 2002 p=513">{{cite journal | last=Quinn | first=C. J. | last2=Price | first2=R. A. | last3=Gadek | first3=P. A. | title=Familial Concepts and Relationships in the Conifer Based on rbcL and matK Sequence Comparisons | journal=Kew Bulletin | publisher=JSTOR | volume=57 | issue=3 | year=2002 | issn=0075-5974 | doi=10.2307/4110984 | page=513}}</ref>,<ref name="Rai Reeves Peakall Olmstead 2008 pp. 658–669">{{cite journal | last=Rai | first=Hardeep S. | last2=Reeves | first2=Patrick A. | last3=Peakall | first3=Rod | last4=Olmstead | first4=Richard G. | last5=Graham | first5=Sean W. | title=Inference of higher-order conifer relationships from a multi-locus plastid data set. | journal=Botany | publisher=Canadian Science Publishing | volume=86 | issue=7 | year=2008 | issn=1916-2790 | doi=10.1139/b08-062 | pages=658–669}}</ref>,<ref name="Springer Science and Business Media LLC 2019 pp. 679–685">{{cite journal | title=One thousand plant transcriptomes and the phylogenomics of green plants | journal=Nature | publisher=Springer Science and Business Media LLC | volume=574 | issue=7780 | year=2019 | issn=0028-0836 | doi=10.1038/s41586-019-1693-2 | pages=679–685}}</ref>, and morphological differences between them are not substantial. Previous recognition of two distinct families, Taxaceae and Cephalotaxaceae (e.g., <ref name="JSTOR">{{cite web | title=A CLADISTIC ANALYSIS OF CONIFERS: PRELIMINARY RESULTS on JSTOR | website=JSTOR | url=https://www.jstor.org/stable/43782212 | access-date=2020-01-05}}</ref>), was based on relatively minor seed morphological details: Taxaceae (excluding ''Cephalotaxus'') has smaller mature seeds growing to {{convert|5|-|8|mm|in}} in 6–8 months, that are not fully enclosed by the aril; in contrast, ''Cephalotaxus'' seeds have a longer maturation period (from 18–20 months), and larger mature seeds ({{convert|12|-|40|mm|in}}) fully enclosed by the aril. However, there are also very clear morphological connections between ''Cephalotaxus'' and other members of Taxaceae <ref name="Doyle 1998 pp. 567–599">{{cite journal | last=Doyle | first=James A. | title=PHYLOGENY OF VASCULAR PLANTS | journal=Annual Review of Ecology and Systematics | publisher=Annual Reviews | volume=29 | issue=1 | year=1998 | issn=0066-4162 | doi=10.1146/annurev.ecolsys.29.1.567 | pages=567–599}}</ref>,<ref name="Stützel Röwekamp 1999 pp. 145–157">{{cite journal | last=Stützel | first=Thomas | last2=Röwekamp | first2=Iris | title=Female reproductive structures in Taxales | journal=Flora | publisher=Elsevier BV | volume=194 | issue=2 | year=1999 | issn=0367-2530 | doi=10.1016/s0367-2530(17)30893-9 | pages=145–157}}</ref>, and considered in tandem with the phylogenetic evidence, there is no compelling need to recognize ''Cephalotaxus'' as a distinct family.


The differences suggested between Taxaceae and Cephalotaxaceae were based on the morphology of the seeds, with Taxaceae having smaller mature seeds growing to {{convert|5|-|8|mm|in}} in 6–8 months and not being fully enclosed by the aril. Cephalotaxaceae seeds show a longer maturation period, ranging from 18–20 months, with the mature seeds fully enclosed in the aril and ranging from {{convert|12|-|40|mm|in}}.


A few botanists{{who|date=April 2013}} have transferred ''Austrotaxus'' to its own family, the Austrotaxaceae, suggesting it may be closer to the [[Podocarpaceae]] than to the other Taxaceae, but genetic evidence does not support this transfer.{{citation needed|date=April 2013}}
===Extant genera===
===Extant genera===
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==References==
* Anderson, E. & Owens, J. N. (2003). Analysing the reproductive biology of Taxus: should it be included in Coniferales? ''Acta Hort.'' 615: 233-234. (conclusion is 'yes')
* Chase, M. W. ''et al.'' (1993). Phylogenetics of seed plants, an analysis of nucleotide sequences from the plastid gene ''rbc''L. ''Ann. Missouri Bot. Gard.'' 80: 528-580.
* Price, R. A. (2003). Generic and familial relationships of the Taxaceae from ''rbc''L and ''mat''K sequence comparisons. ''Acta Hort.'' 615: 235-237.


==Footnotes==
==Footnotes==

Revision as of 06:13, 5 January 2020

Taxaceae
Temporal range:
Middle Eocene - Present 44 mya - 0[1]
Foliage and mature arils of a yew plant
Scientific classification Edit this classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Gymnospermae
Division: Pinophyta
Class: Pinopsida
Order: Cupressales
Family: Taxaceae
S.F.Gray
Genera

Taxaceae (/tækˈseɪsii/), commonly called the yew family, is a coniferous family which includes seven genera and about 30 species of plants, or in older interpretations three genera and 7 to 12 species.

They are many-branched, small trees and shrubs. The leaves are evergreen, spirally arranged, often twisted at the base to appear 2-ranked. They are linear to lanceolate, and have pale green or white stomatal bands on the undersides. The plants are dioecious, rarely monoecious. The male cones are 2–5 millimetres (0.079–0.197 in) long, and shed pollen in the early spring. The female cones are highly reduced, with just one ovuliferous scale and one seed. As the seed matures, the ovuliferous scale develops into a fleshy aril partly enclosing the seed. The mature aril is brightly coloured, soft, juicy and sweet, and is eaten by birds which then disperse the hard seed undamaged in their droppings. However, the seeds are highly poisonous to humans, containing the poisons taxine and taxol.[2]

Classification

Taxaceae is now generally included with all other conifers in the order Pinales, as DNA analysis has shown that the yews are phylogenetically nested in the Pinales [3], a conclusion supported by micromorphology studies [4]. Formerly they were often treated as distinct from other conifers by placing them in a separate order Taxales. Ernest Henry Wilson referred to Taxaceae as taxads in his book ”1916, Conifers and taxads of Japan".[5]

Cephalotaxus is now included in Taxaceae, rather than being recognized as the sole genus in its own family, Cephalotaxaceae. The broadly defined Taxaceae (including Cephalotaxus) comprises six extant genera and about 30 species overall.

Phylogenetic evidence strongly supports a very close relationship between Cephalotaxus and other members of Taxaceae[6],[7],[8], and morphological differences between them are not substantial. Previous recognition of two distinct families, Taxaceae and Cephalotaxaceae (e.g., [9]), was based on relatively minor seed morphological details: Taxaceae (excluding Cephalotaxus) has smaller mature seeds growing to 5–8 millimetres (0.20–0.31 in) in 6–8 months, that are not fully enclosed by the aril; in contrast, Cephalotaxus seeds have a longer maturation period (from 18–20 months), and larger mature seeds (12–40 millimetres (0.47–1.57 in)) fully enclosed by the aril. However, there are also very clear morphological connections between Cephalotaxus and other members of Taxaceae [10],[11], and considered in tandem with the phylogenetic evidence, there is no compelling need to recognize Cephalotaxus as a distinct family.


Extant genera

Image Genus Living species
Amentotaxus – Catkin-yew Pilg.
Austrotaxus – New Caledonia yew Compton
Cephalotaxus – Plum yew Siebold & Zucc. ex Endl.
Pseudotaxus – White-berry yew W.C.Cheng
Taxus – Common yew L.
Torreya – Nutmeg yew Arn.

Footnotes

Wikimedia Commons has media related to Taxaceae.
Wikispecies has information related to Taxaceae.
  1. ^ a b Manchester, S.R. (1994). "Fruits and Seeds of the Middle Eocene Nut Beds Flora, Clarno Formation, Oregon". Palaeontographica Americana. 58: 30–31.
  2. ^ Yew Poisoning: MedLine Plus Medical Encyclopedia
  3. ^ Chase, Mark W.; Soltis, Douglas E.; Olmstead, Richard G.; Morgan, David; Les, Donald H.; Mishler, Brent D.; Duvall, Melvin R.; Price, Robert A.; Hills, Harold G.; Qiu, Yin-Long; Kron, Kathleen A.; Rettig, Jeffrey H.; Conti, Elena; Palmer, Jeffrey D.; Manhart, James R.; Sytsma, Kenneth J.; Michaels, Helen J.; Kress, W. John; Karol, Kenneth G.; Clark, W. Dennis; Hedren, Mikael; Gaut, Brandon S.; Jansen, Robert K.; Kim, Ki-Joong; Wimpee, Charles F.; Smith, James F.; Furnier, Glenn R.; Strauss, Steven H.; Xiang, Qui-Yun; Plunkett, Gregory M.; Soltis, Pamela S.; Swensen, Susan M.; Williams, Stephen E.; Gadek, Paul A.; Quinn, Christopher J.; Eguiarte, Luis E.; Golenberg, Edward; Learn, Gerald H.; Graham, Sean W.; Barrett, Spencer C. H.; Dayanandan, Selvadurai; Albert, Victor A. (1993). "Phylogenetics of Seed Plants: An Analysis of Nucleotide Sequences from the Plastid Gene rbcL". Annals of the Missouri Botanical Garden. 80 (3). JSTOR: 528. doi:10.2307/2399846. ISSN 0026-6493.
  4. ^ Anderson, E.; Owens, J.N. (2003). "ANALYZING THE REPRODUCTIVE BIOLOGY OF TAXUS: SHOULD IT BE INCLUDED IN CONIFERALES?". Acta Horticulturae (615). International Society for Horticultural Science (ISHS): 233–234. doi:10.17660/actahortic.2003.615.22. ISSN 0567-7572.
  5. ^ taxad (plant family) : see Taxaceae; britannica
  6. ^ Quinn, C. J.; Price, R. A.; Gadek, P. A. (2002). "Familial Concepts and Relationships in the Conifer Based on rbcL and matK Sequence Comparisons". Kew Bulletin. 57 (3). JSTOR: 513. doi:10.2307/4110984. ISSN 0075-5974.
  7. ^ Rai, Hardeep S.; Reeves, Patrick A.; Peakall, Rod; Olmstead, Richard G.; Graham, Sean W. (2008). "Inference of higher-order conifer relationships from a multi-locus plastid data set". Botany. 86 (7). Canadian Science Publishing: 658–669. doi:10.1139/b08-062. ISSN 1916-2790.
  8. ^ "One thousand plant transcriptomes and the phylogenomics of green plants". Nature. 574 (7780). Springer Science and Business Media LLC: 679–685. 2019. doi:10.1038/s41586-019-1693-2. ISSN 0028-0836.
  9. ^ "A CLADISTIC ANALYSIS OF CONIFERS: PRELIMINARY RESULTS on JSTOR". JSTOR. Retrieved 2020-01-05.
  10. ^ Doyle, James A. (1998). "PHYLOGENY OF VASCULAR PLANTS". Annual Review of Ecology and Systematics. 29 (1). Annual Reviews: 567–599. doi:10.1146/annurev.ecolsys.29.1.567. ISSN 0066-4162.
  11. ^ Stützel, Thomas; Röwekamp, Iris (1999). "Female reproductive structures in Taxales". Flora. 194 (2). Elsevier BV: 145–157. doi:10.1016/s0367-2530(17)30893-9. ISSN 0367-2530.
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