# Amentotaxus
**Amentotaxus** is a small genus of conifers in the yew family ([Taxaceae](https://www.edgepedia.org/taxaceae)), commonly called catkin yews, comprising about seven accepted species of dioecious evergreen trees and shrubs native from the eastern Himalaya to central China and Taiwan[1](https://powo.science.kew.org/taxon/urn%3Alsid%3Aipni.org%3Anames%3A38989-1) • [2](https://conifersociety.org/conifers/amentotaxus/). The genus was described in 1916 by the German botanist Robert Knud Friedrich Pilger in *Botanische Jahrbücher für Systematik, Pflanzengeschichte und Pflanzengeographie*, and its name refers to the conspicuous pendulous male catkins[1](https://powo.science.kew.org/taxon/urn%3Alsid%3Aipni.org%3Anames%3A38989-1) • [2](https://conifersociety.org/conifers/amentotaxus/).
| Key fact | Detail |
|---|---|
| Scientific name | *Amentotaxus* Pilg., first published in Bot. Jahrb. Syst. 54: 41 (1916)[1](https://powo.science.kew.org/taxon/urn%3Alsid%3Aipni.org%3Anames%3A38989-1) |
| Species count | Kew's Plants of the World Online accepts 7 species (plus one named hybrid); other treatments recognize five or six[1](https://powo.science.kew.org/taxon/urn%3Alsid%3Aipni.org%3Anames%3A38989-1) • [3](https://pmc.ncbi.nlm.nih.gov/articles/PMC11779735/) |
| Native range | East Himalaya to central China and Taiwan; native to Cambodia, north-central, south-central and southeast China, East Himalaya, Laos, Myanmar, Taiwan, Tibet, and Vietnam[1](https://powo.science.kew.org/taxon/urn%3Alsid%3Aipni.org%3Anames%3A38989-1) |
| Phylogenetic position | Sister to *Torreya*; together the two genera form the tribe Torreyeae, sister to the other Taxaceae genera[4](https://www.tandfonline.com/doi/full/10.1080/23802359.2019.1607592) • [5](https://pubmed.ncbi.nlm.nih.gov/28819805/) |
| Diagnostic morphology | Opposite leaves and terminal racemes of pollen strobili, unique among Taxaceae genera; leaves white-banded beneath[6](https://www.torreyaguardians.org/taxaceae-key-1998-cope.pdf) • [7](https://www.cambridge.org/core/books/abs/evolution-of-the-arborescent-gymnosperms/amentotaxus/0E5C4C32B98AA6A5275EE98150877FEE) |
| Fossil record | North America from the Upper Cretaceous (Santonian) to the Miocene; Europe from the Paleocene to the Upper Miocene[8](https://doi.org/10.1111/j.1759-6831.2009.00001.x) |
| Conservation | Several species have extremely small populations; *A. yunnanensis* is a listed Plant Species with Extremely Small Population in China[4](https://www.tandfonline.com/doi/full/10.1080/23802359.2019.1607592) |
## Description and identification
Species of *Amentotaxus* are dioecious, evergreen, slow-growing, resiniferous slender trees of moderate size, monopodial when young and becoming irregularly shaped with maturity, with spreading to pendulous sickle-shaped leaves that are conspicuously white-banded beneath[7](https://www.cambridge.org/core/books/abs/evolution-of-the-arborescent-gymnosperms/amentotaxus/0E5C4C32B98AA6A5275EE98150877FEE). Two characters separate the genus from all other genera in the family: the leaves are opposite rather than alternate, and the pollen strobili are borne in terminal racemes[6](https://www.torreyaguardians.org/taxaceae-key-1998-cope.pdf). Compared with the vegetatively similar and much more common *Cephalotaxus*, *Amentotaxus* has larger and broader, more horizontally held leaves, simpler seed-bearing structures, and more complexly structured male ones[7](https://www.cambridge.org/core/books/abs/evolution-of-the-arborescent-gymnosperms/amentotaxus/0E5C4C32B98AA6A5275EE98150877FEE). All species occur at relatively high altitudes in damp or shady places such as along stream banks or ravines[6](https://www.torreyaguardians.org/taxaceae-key-1998-cope.pdf).
## Species
Kew's Plants of the World Online accepts seven species: *[Amentotaxus argotaenia](https://www.edgepedia.org/amentotaxus-argotaenia)*, *A. assamica*, *A. formosana*, *A. hatuyenensis*, *A. hekouensis*, *A. poilanei*, and *A. yunnanensis*, together with the named hybrid *Amentotaxus × hybridia*[1](https://powo.science.kew.org/taxon/urn%3Alsid%3Aipni.org%3Anames%3A38989-1). Other treatments recognize five or six species, and the count depends on the classification system used[3](https://pmc.ncbi.nlm.nih.gov/articles/PMC11779735/). The center of diversity lies in the Sino-Vietnamese karst highlands[9](https://plantaedb.com/taxa/phylum/pinophyta/class/pinopsida/subclass/cupressidae/order/cupressales/family/taxaceae/genus/amentotaxus).
Species boundaries within the genus are difficult to draw with standard DNA barcodes. In a study using plastid and nuclear barcode data, the standard three-plastid-barcode combination (rbcL + matK + trnH-psbA) identified only two of six species and the four-barcode combination including ITS only three; the plastid gene spacer clpP-rps12 alone delineated four species and was proposed as an *Amentotaxus*-specific barcode[10](https://pmc.ncbi.nlm.nih.gov/articles/PMC13181900/). The same study found that *A. poilanei* appears to have recently diverged from *A. hekouensis* as a budding speciation event, that one sample's discordant placement in nuclear and plastid trees suggests a hybrid origin that frustrates plastome-based identification of *A. assamica*, and that an undescribed cryptic species may exist in north Myanmar[10](https://pmc.ncbi.nlm.nih.gov/articles/PMC13181900/).
## Phylogeny and classification
The genus's placement has moved between families. Early molecular work using 18S rRNA sequences found *Amentotaxus* closer to *Torreya* than to *Cephalotaxus*, supporting its classification as a member of Taxaceae[11](https://www.researchgate.net/publication/15533610_The_phylogenetic_positions_of_the_conifer_genera_Amentotaxus_Phyllocladus_and_Nageia_inferred_from_18S_rRNA_sequences). Analysis of chloroplast matK genes and nuclear ITS sequences for all six genera of Taxaceae and Cephalotaxaceae resolved two clades among the taxad genera, *Torreya*/*Amentotaxus* and *Taxus*/*Pseudotaxus*/*Austrotaxus*, corresponding to Janchen's tribes Torreyeae and Taxeae, and refuted views that *Amentotaxus* should be excluded from Taxaceae[12](https://www.sciencedirect.com/science/article/abs/pii/S1055790399907108). A phylogeny of Taxaceae using multiple markers fully supported the two monophyletic tribes, with Torreyeae comprising *Amentotaxus* and *Torreya*[5](https://pubmed.ncbi.nlm.nih.gov/28819805/). A chloroplast-genome study of *Amentotaxus yunnanensis* likewise found that *Amentotaxus* and *Torreya* form a sister group to the other genera of Taxaceae[4](https://www.tandfonline.com/doi/full/10.1080/23802359.2019.1607592).
Some authors have treated the genus differently. Christopher N. Page, of the [University of Exeter](https://www.edgepedia.org/university-of-exeter), places *Amentotaxus* in Cephalotaxaceae in his treatment of arborescent gymnosperms[7](https://www.cambridge.org/core/books/abs/evolution-of-the-arborescent-gymnosperms/amentotaxus/0E5C4C32B98AA6A5275EE98150877FEE), and one analysis of five chloroplast and one nuclear marker regions supported dividing the species among three allied families, Taxaceae, Cephalotaxaceae, and Amentotaxaceae[13](https://www.mdpi.com/2311-7524/6/1/19). The prevailing molecular evidence, however, supports the sister relationship between *Torreya* and *Amentotaxus* within Taxaceae, a result previously accepted by multiple molecular analyses and morphological evidence[14](https://doi.org/10.1111/jse.12482).
## Chloroplast genome
The complete chloroplast genome of *Amentotaxus yunnanensis*, a threatened species with extremely small populations in China, is 137,594 bp in length with a total GC content of 35.9%[4](https://www.tandfonline.com/doi/full/10.1080/23802359.2019.1607592). Like other conifers, it lacks inverted repeats. It contains 118 unique genes: 83 protein-coding genes, 31 tRNA genes, and four rRNA genes; 16 genes contain a single intron and *ycf3* contains two[4](https://www.tandfonline.com/doi/full/10.1080/23802359.2019.1607592). Comparative work across Taxaceae shows that the plastomes of all 12 studied species from four genera share an rpl23-rps3 cluster downstream of IRB and lack the IRA region, and that *Amentotaxus* and *Torreya* form one of the two main plastome clades, at the basal position[15](https://www.frontiersin.org/journals/genetics/articles/10.3389/fgene.2019.01295/pdf).
## Fossil history
*Amentotaxus* is a paleoendemic: it is now confined to eastern Asia but has an extensive fossil record in North America and Europe[8](https://doi.org/10.1111/j.1759-6831.2009.00001.x). Fossil leaves are readily recognized by their broad needle-like form with a pair of prominent stomatal bands and distinctive epidermal anatomy[8](https://doi.org/10.1111/j.1759-6831.2009.00001.x). In North America the genus extends from the Upper Cretaceous ([Santonian](https://www.edgepedia.org/santonian)) to the Miocene, and in Europe from the [Paleocene](https://www.edgepedia.org/paleocene) to the Upper Miocene[8](https://doi.org/10.1111/j.1759-6831.2009.00001.x). A review by the paleobotanist Bruce LePage accepts reports as old as the Aptian stage of the [Cretaceous](https://www.edgepedia.org/cretaceous) from western Canada and Greenland, with later Cretaceous records in Asia and North America[8](https://doi.org/10.1111/j.1759-6831.2009.00001.x).
Middle to Late Jurassic fossils from Daohuguo, in northeastern China, are resolved as sister taxa to extant *Amentotaxus*, with *Marskea jurassica* from the Middle Jurassic of Yorkshire, England, sister to both; the clade is defined by naked seed stalks that each bear a single seed[16](https://pmc.ncbi.nlm.nih.gov/articles/PMC8288717/). The fossil record shows morphological stasis: the Daohuguo material could reasonably be assigned to the extant genus, though insufficient information on pollen organs prevents placing it unequivocally in the crown group[16](https://pmc.ncbi.nlm.nih.gov/articles/PMC8288717/). In Europe the genus was present from the Paleocene to the Upper Miocene, represented by a single species referred to as *Amentotaxus gladifolia*[2](https://conifersociety.org/conifers/amentotaxus/).
## Conservation
The genus is described as particularly vulnerable. Its species have small populations and low genetic diversity, a legacy of fragmented mountain habitats, limited pollination and seed dispersal, and inbreeding risk[3](https://pmc.ncbi.nlm.nih.gov/articles/PMC11779735/). *Amentotaxus yunnanensis* is a typical Plant Species with Extremely Small Population (PSESP) in China and has received limited research and conservation attention[4](https://www.tandfonline.com/doi/full/10.1080/23802359.2019.1607592). *Amentotaxus formosana*, an endangered glacial relict insular species in Taiwan, survives in fragmented mountainous populations; a fine-scale genetic study of its populations was designed to inform the delineation of genetic conservation units[3](https://pmc.ncbi.nlm.nih.gov/articles/PMC11779735/). The potential cryptic species in north Myanmar identified by [DNA barcoding](https://www.edgepedia.org/dna-barcoding) adds an unnamed lineage to conservation planning[10](https://pmc.ncbi.nlm.nih.gov/articles/PMC13181900/).
## References
1. [Amentotaxus Pilg., Plants of the World Online, Royal Botanic Gardens, Kew](https://powo.science.kew.org/taxon/urn%3Alsid%3Aipni.org%3Anames%3A38989-1)
2. [Amentotaxus, American Conifer Society](https://conifersociety.org/conifers/amentotaxus/)
3. [Assessment of genetic conservation units of an endangered glacial relict insular species, Amentotaxus formosana (PMC)](https://pmc.ncbi.nlm.nih.gov/articles/PMC11779735/)
4. [Characterization of complete chloroplast genome of Amentotaxus yunnanensis (Taxaceae), Mitochondrial DNA Part B](https://www.tandfonline.com/doi/full/10.1080/23802359.2019.1607592)
5. [Diversity and evolution of leaf anatomical characters in Taxaceae s.l. (PubMed abstract)](https://pubmed.ncbi.nlm.nih.gov/28819805/)
6. [Taxaceae: The Genera and Cultivated Species, The Botanical Review (Torreya Guardians copy)](https://www.torreyaguardians.org/taxaceae-key-1998-cope.pdf)
7. [Christopher N. Page, Chapter 17: Amentotaxus, in Evolution of the Arborescent Gymnosperms, Cambridge University Press](https://www.cambridge.org/core/books/abs/evolution-of-the-arborescent-gymnosperms/amentotaxus/0E5C4C32B98AA6A5275EE98150877FEE)
8. [Manchester, Chen, Lu & Uemura (2009). Eastern Asian endemic seed plant genera and their paleogeographic history throughout the Northern Hemisphere. Journal of Systematics and Evolution](https://doi.org/10.1111/j.1759-6831.2009.00001.x)
9. [Amentotaxus, PlantaeDB](https://plantaedb.com/taxa/phylum/pinophyta/class/pinopsida/subclass/cupressidae/order/cupressales/family/taxaceae/genus/amentotaxus)
10. [DNA barcodes analyses provide insights into species delineation and possible cryptic species in Amentotaxus (PMC)](https://pmc.ncbi.nlm.nih.gov/articles/PMC13181900/)
11. [Chaw et al. (1995). The phylogenetic positions of the conifer genera Amentotaxus, Phyllocladus, and Nageia inferred from 18S rRNA sequences. Journal of Molecular Evolution](https://www.researchgate.net/publication/15533610_The_phylogenetic_positions_of_the_conifer_genera_Amentotaxus_Phyllocladus_and_Nageia_inferred_from_18S_rRNA_sequences)
12. [Cheng et al. (2000). Phylogeny of Taxaceae and Cephalotaxaceae genera inferred from chloroplast matK gene and nuclear rDNA ITS region. Molecular Phylogenetics and Evolution](https://www.sciencedirect.com/science/article/abs/pii/S1055790399907108)
13. [Phylogenetics of Taxus Using the Internal Transcribed Spacers of Nuclear Ribosomal DNA and Plastid trnL-F Regions, Horticulturae](https://www.mdpi.com/2311-7524/6/1/19)
14. [Zhang (2019). Plastome phylogenomic analysis of Torreya (Taxaceae). Journal of Systematics and Evolution](https://doi.org/10.1111/jse.12482)
15. [Comparative Genomic Analysis Reveals the Mechanism Driving the Diversification of Plastomic Structure in Taxaceae Species, Frontiers in Genetics](https://www.frontiersin.org/journals/genetics/articles/10.3389/fgene.2019.01295/pdf)
16. [Middle–Late Jurassic fossils from northeastern China reveal morphological stasis in the catkin-yew (PMC)](https://pmc.ncbi.nlm.nih.gov/articles/PMC8288717/)
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*Topic: Encyclopedia › Life and health › Plants and algae › Seed plants › Conifers and other gymnosperms › Conifers › Yews, plum yews, and allies (Taxaceae and Cephalotaxaceae) › Amentotaxus (catkin yews)*
*Initially written Sep 17, 2026 · Reviewed: Sep 30, 2026; Oct 21, 2026 · Edited: Sep 30, 2026; Oct 11, 2026; Oct 15, 2026; Oct 21, 2026 · Last review: Oct 21, 2026*
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