Alloberberis trifoliolata (Moric.) C.C.Yu & F.K.Chung

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Credits

Article from Bean's Trees and Shrubs Hardy in the British Isles

Recommended citation
'Alloberberis trifoliolata' from the website Trees and Shrubs Online (treesandshrubsonline.org/articles/alloberberis/alloberberis-trifoliolata/). Accessed 2025-04-29.

Family

Berberidaceae

Genus

Alloberberis

Common Names

Agarito

Synonyms

Alloberberis trifoliolata var. glauca (I.M.Johnst.) C.C.Yu & F.K.Chung
Berberis trifoliolata Moric.
Mahonia trifoliolata (Moric.) Fedde

Other taxa in genus

Glossary

glaucous: Grey-blue often from superficial layer of wax (bloom).
variety: (var.) Taxonomic rank (varietas) grouping variants of a species with relatively minor differentiation in a few characters but occurring as recognisable populations. Often loosely used for rare minor variants more usefully ranked as forms.

References

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Credits

Article from Bean's Trees and Shrubs Hardy in the British Isles

Recommended citation
'Alloberberis trifoliolata' from the website Trees and Shrubs Online (treesandshrubsonline.org/articles/alloberberis/alloberberis-trifoliolata/). Accessed 2025-04-29.

Mahonia trifoliolata is a widespread species of northern Mexico and southern Texas, New Mexico and Arizona. Some have bluer leaves than others, but this varies along a spectrum and the name var. glauca is rarely used today in either botany or horticulture. (Wild plant, Gillespie Co., Texas, USA; 2 March 2024). Image Julian Sutton.

Editorial Note

See the genus entry for Alloberberis for a brief discussion of the taxonomy of this species. The text below is heavily adapted from Bean to take account of the latest understanding of the systematics.

An erect, rigid shrub 6 or 8 ft high, with only three leaflets to each leaf. Leaflets lustrous green, glaucous or almost white, shaped like a spear-head, 1 to 2 in. long, 1⁄4 to 3⁄5 in. wide, tapering to a long, spine-tipped point, and bulging at each side into one or two spine-tipped lobes. Flowers yellow, borne in short corymbs. Fruits oval or roundish, black with a blue bloom.

This rare shrub ranges from W. Texas to N. Mexico, and is only hardy against a sunny wall, or in exceptionally mild districts. There was once an old bush, 8 ft high, growing against the house wall at Bayfordbury in Herts.This variety differs from all the other cultivated mahonias in the glaucous-white leaves with only three leaflets. It was introduced to Britain in 1839 by Hartweg, who collected the seeds in Mexico on the road from Zacatecas to San Luis Potosi.

Bean worked on the assumption that the glaucous- or almost white-leaved plants familiar from cultivation and frequently seen in the wild belonged to var. glauca (I.M.Johnst.) C.C.Yu & F.K.Chung, and that the green-leaved plants confined (so Bean said) to southern Texas represented the typical state. However, the Flora of North America (2025) does not recognise infraspecific taxa for this species, noting that ‘weakly and strongly glaucous plants are often found in the same population’. Accordingly, we reduce var. glauca to synonymy with the type.

Forms of Mahonia trifoliolata with reddish backs to the sepals are particularly attractive (wild plant, Jeff Davis Co., Texas, USA; 9 March 2024). Image Julian Sutton.

Mahonia trifoliolata commonly grows on stony hillsides (Jeff Davis Co., Texas, USA; 9 March 2024). Image Julian Sutton.

Mahonia trifoliolata fruits are dispersed by birds, hence it is most often seen growing at at the base of a tree or larger shrub in the wild (Gillespie Co., Texas, USA; 2 March 2024). Image Julian Sutton.

An individual of Mahonia trifoliolata with greener leaves than most. Soft growing conditions in gardens may contribute to this, although other plants in the same garden had rather more glaucous foliage (cultivated plant, Lady Bird Johnson Wildflower Center, Austin, Texas, USA; 12 March 2024). Image Julian Sutton.

Mahonia trifoliolata at Plas Cadnant, Anglesey, north Wales. 5 September 2019. Image John Anderson.

Mahonia trifoliolata. University of British Columbia Botanic Garden, Vancouver, Canada. 1 March 2019. Image John Anderson.