Taxaceae

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

Taxaceae Temporal range: Triassic–Recent PreꞒ Ꞓ O S D C P T J K Pg N
Foliage and mature arils of a yew plant
Scientific classification
Kingdom:	Plantae
Clade:	Tracheophytes
Division:	Pinophyta
Class:	Pinopsida
Order:	Pinales
Family:	Taxaceae S.F.Gray
Genera
Amentotaxus Austrotaxus Cephalotaxus †Diploporus Pseudotaxus †Sommerxylon Taxus Torreya
Synonyms
Austrotaxaceae Cephalotaxaceae

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 to a single seed. As the seed matures, a fleshy aril partly encloses it. The developmental origin of the aril is unclear, but it may represent a fused pair of swollen leaves.[1] 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 1916 book.[5]

The broadly defined Taxaceae (including Cephalotaxus) comprises six extant genera and about 30 species overall. Cephalotaxus is now included in Taxaceae, rather than being recognized as the core of its own family, Cephalotaxaceae. 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 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 (or other genera in Taxaceae) as a distinct family[6],[7].

Extant genera

Genus	Species	Image
Amentotaxus Pilg. – Catkin-yew	Amentotaxus argotaenia - Catkin yew Amentotaxus assamica - Assam catkin yew Amentotaxus formosana - Taiwan catkin yew Amentotaxus poilanei - Poilane's catkin yew Amentotaxus yunnanensis - Yunnan catkin yew	Amentotaxus argotaenia
Austrotaxus Compton – New Caledonia yew	Austrotaxus spicata - New Caledonia yew or southern yew	Austrotaxus spicata
Cephalotaxus Siebold & Zucc. ex Endl. – Plum yew	Cephalotaxus fortunei - Chinese plum-yew Cephalotaxus griffithii - Griffith's plum yew Cephalotaxus hainanensis - Hainan plum-yew Cephalotaxus harringtonii - Korean plum yew, Japanese plum-yew Cephalotaxus koreana - Korean plum yew Cephalotaxus lanceolata - Gongshan plum yew Cephalotaxus latifolia - Broad-leaved plum yew Cephalotaxus mannii - Mann's yew plum Cephalotaxus oliveri - Oliver's plum yew Cephalotaxus sinensis - Chinese plum yew Cephalotaxus wilsoniana - Taiwan plum yew, Taiwan cow's-tail pine, and Wilson plum yew	Cephalotaxus sinensis
Pseudotaxus W.C.Cheng – White-berry yew	Pseudotaxus chienii - the whiteberry yew
Taxus L. – Common yew	Taxus baccata European yew Taxus biternata Delicate branch yew Taxus brevifolia Pacific yew, western yew Taxus caespitosa Caespitosa yew Taxus calcicola Asian limestone yew Taxus canadensis Canada yew Taxus celebica Celebes yew Taxus chinensis China yew Taxus contorta West Himalayan yew Taxus cuspidata Rigid branch yew, Japanese yew Taxus fastigiata Irish yew Taxus floridana Florida yew Taxus florinii Florin yew Taxus fuana, possible synonym of T. contorta Taxus globosa Mesoamerican yew Taxus kingstonii Kingston yew Taxus mairei Maire yew Taxus obscura Obscure yew Taxus ocreata Scaly yew Taxus phytonii Phyton yew Taxus recurvata English yew Taxus rehderiana Rehder yew Taxus scutata Scutaceous yew Taxus suffnessii Suffness yew Taxus sumatrana Sumatera yew Taxus umbraculifera Umbrelliform yew Taxus wallichiana Wallich yew, East Himalayan yew	Taxus brevifolia
Torreya Arn. – Nutmeg yew	Torreya californica - California torreya Torreya fargesii - Farges nutmeg tree Torreya grandis - Chinese nutmeg yew Torreya jackii - Jack's nutmeg tree, longleaf torreya, Jack torreya, and weeping torreya Torreya nucifera - kaya, Japanese torreya, or Japanese nutmeg-yew Torreya taxifolia - Florida torreya or gopher wood †Torreya clarnensis[12]	Torreya californica

Footnotes

1. Dörken, Veit Martin; Nimsch, Hubertus; Rudall, Paula J (2018-08-22). "Origin of the Taxaceae aril: evolutionary implications of seed-cone teratologies in Pseudotaxus chienii". Annals of Botany. Oxford University Press (OUP). 123 (1): 133–143. doi:10.1093/aob/mcy150. ISSN 0305-7364. PMC 6344100. PMID 30137225.
2. Yew Poisoning: MedLine Plus Medical Encyclopedia
3. Chase, M. W.; Soltis, D. E.; et al. (1993). "Phylogenetics of Seed Plants: An Analysis of Nucleotide Sequences from the Plastid Gene rbcL" (PDF). Annals of the Missouri Botanical Garden. JSTOR. 80 (3): 528. doi:10.2307/2399846. ISSN 0026-6493. JSTOR 2399846.
4. Anderson, E.; Owens, J.N. (2003). "Analyzing the Reproductive Biology of Taxus: Should It be Included in Coniferales?". Acta Horticulturae. International Society for Horticultural Science (ISHS) (615): 233–234. doi:10.17660/actahortic.2003.615.22. ISSN 0567-7572.
5. Wilson, Ernest Henry (1916). The conifers and taxads of Japan. Issued December 30, 1916. Cambridge: University Press. doi:10.5962/bhl.title.17457.
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. JSTOR. 57 (3): 513. doi:10.2307/4110984. ISSN 0075-5974. JSTOR 4110984.
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. Canadian Science Publishing. 86 (7): 658–669. doi:10.1139/b08-062. ISSN 1916-2790.
8. One Thousand Plant Transcriptomes Initiative (2019). "One thousand plant transcriptomes and the phylogenomics of green plants". Nature. Springer Science and Business Media LLC. 574 (7780): 679–685. doi:10.1038/s41586-019-1693-2. ISSN 0028-0836. PMC 6872490. PMID 31645766.
9. Hart, Jeffrey A. (1987). "A Cladistic Analysis of Conifers: Preliminary Results". Journal of the Arnold Arboretum. 68 (3): 269–307. JSTOR 43782212.
10. Doyle, James A. (1998). "Phylogeny of Vascular Plants". Annual Review of Ecology and Systematics. Annual Reviews. 29 (1): 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. Elsevier BV. 194 (2): 145–157. doi:10.1016/s0367-2530(17)30893-9. ISSN 0367-2530.
12. Manchester, S.R. (1994). "Fruits and Seeds of the Middle Eocene Nut Beds Flora, Clarno Formation, Oregon". Palaeontographica Americana. 58: 30–31.