Buxaceae Plant Family

About the Buxaceae or Boxwood Family

Buxaceae is a family of plants that includes only six genera and approximately 90 species. Members of this family are distributed across the world, with most species found in tropical and subtropical regions. Buxaceae is taxonomically classified in the order Buxales, which is thought to be one of the earliest diverging lineages of eudicots, a major group of flowering plants. Plants in this family are known for their woody habit, simple leaves, and small flowers that lack petals and sepals. The family has both ecological and economic importance, as some species are used in traditional medicine or horticulture.

Taxonomy and Classification

Buxaceae is a small family of flowering plants that is classified in the order Buxales. The family includes six genera: Buxus, Haptanthus, Notobuxus, Pachysandra, Sarcococca, and Styloceras. The genus Buxus is the largest and most well- genus in the family, containing over 70 species of broadleaf evergreen shrubs and trees.

Buxaceae has been associated with several other families, including Simmondsiaceae, Cyrillaceae, and Celastraceae, but molecular evidence supports its recognition as a distinct family. Within Buxaceae, there are no subfamilies, although some authors have recognized two major groups based on morphological features: the Buxus group and the Pachysandra group.

Overall, the taxonomy and classification of Buxaceae are still being refined as new molecular data become available. However, it is clear that this family represents an early- lineage of eudicots that has unique evolutionary relationships and characteristics.

Morphology and Characteristics

Plants in the Buxaceae family are known for their woody habit, which can range from small shrubs to trees up to 20 meters tall. The leaves of Buxaceae plants are simple and alternate, with entire margins and no stipules. The arrangement of the leaves may be distichous or spiral, depending on the genus.

The flowers of Buxaceae are small, unisexual, and lack petals and sepals. They are typically arranged in axillary or terminal spikes or racemes. The male flowers consist of a single stamen and are usually more prominent than the female flowers, which have a superior ovary and one carpel. In some genera, such as Haptanthus, the female flowers are reduced to a single style that lacks an ovary.

The fruit of Buxaceae is usually a drupe or capsule that contains one or more seeds. The seeds are often covered with a fleshy aril, which is attractive to birds and other animals that aid in seed dispersal.

Buxaceae plants exhibit a variety of growth habits, including erect or prostrate forms, epiphytic forms, and creeping or climbing forms. Some species are adapted to shade or low- conditions, while others prefer full sun. Overall, the morphology and characteristics of Buxaceae plants reflect their diverse ecological roles and adaptations.

Distribution and Habitat

Buxaceae plants are distributed across the world, with species found in Asia, Europe, Africa, North and South America, and Oceania. The greatest diversity of Buxaceae species is found in tropical and subtropical regions, although some temperate species also occur.

Members of the genus Buxus are particularly widespread, with species found in Europe, Asia, Africa, and North America. Other genera, such as Pachysandra and Sarcococca, have more limited distributions, being mostly confined to Asia.

Buxaceae plants can be found growing in a variety of habitats, including forests, woodlands, grasslands, scrublands, and rocky outcrops. Some species are adapted to specific environmental conditions, such as wet or dry soils, while others are more generalist and can thrive in a range of soil types and moisture levels.

Overall, the distribution of Buxaceae reflects their diverse ecological roles and adaptations, as well as historical biogeographic events that have shaped plant diversity across the globe.

Economic and Ecological Importance

Buxaceae plants have both economic and ecological importance. Some species in this family are used for traditional medicine, while others are cultivated for their ornamental value or commercial uses.

Members of the genus Buxus are widely used in horticulture as ornamental shrubs or topiary plants. Buxus sempervirens, commonly known as common boxwood, is a popular landscape plant that is valued for its evergreen foliage, dense growth habit, and tolerance of heavy pruning. Other species of Buxus are also used in bonsai, topiary, and hedging.

Several Buxaceae species have been used in traditional medicine to treat a range of conditions, such as diarrhea, fever, and rheumatism. For example, Sarcococca saligna has been used in Chinese medicine to treat joint pain and swelling.

Ecologically, Buxaceae plants play important roles in ecosystems by providing habitat for animals, contributing to soil health, and supporting biodiversity. Some species are also important food sources for wildlife. For example, the fruit of Pachysandra procumbens, commonly known as Allegheny spurge, is consumed by several bird species, including the northern bobwhite and eastern towhee.

Overall, Buxaceae plants represent an important component of natural and cultural landscapes, with both aesthetic and practical value for humans and other organisms.

Notable Species

Some notable species within the Buxaceae family include:

  • Buxus sempervirens: Also known as common boxwood, this species is a popular ornamental shrub that is valued for its evergreen foliage and dense growth habit. It is native to Europe, Asia, and North Africa, and has been cultivated since ancient times for use in hedges, topiary, and other landscape designs.

  • Pachysandra terminalis: This species, commonly known as Japanese spurge, is a low- groundcover plant that is often used in landscaping. It is valued for its shade tolerance, evergreen leaves, and white flower spikes that appear in early spring.

  • Sarcococca ruscifolia: Also called fragrant sweetbox, this species is a small evergreen shrub that is native to China and Japan. It produces highly fragrant white flowers in late winter or early spring, followed by red or black berries. The plant is often used in shady areas of the garden and is valued for its fragrance.

  • Haptanthus hazlettii: This monotypic genus is represented by a single species, which is endemic to Mexico. It is a small tree or shrub that produces unusual, tubular flowers with an irregular shape. The plant is rare in cultivation and is considered endangered in the wild due to habitat loss.

  • Styloceras capensis: This species is a small tree or shrub that is native to South Africa. It is notable for its distinctive bark, which peels off in thin, papery flakes. The plant is sometimes cultivated for its ornamental value and is also used in traditional medicine.

These species represent just a few examples of the diversity and ecological significance of the Buxaceae family.