Introduction to the Aquifoliaceae Family

The Aquifoliaceae is a small but interesting family of mostly evergreen shrubs and trees, often with glossy, spiny leaves that are easy to recognize from holiday decorations.

Where I grew up, there were no native Ilex species, but the English holly, Ilex aquifolium, was introduced there and is rather invasive, able to grow deep in the forest canopy where its seeds are deposited by birds who eat its berry-like fruits. So my first introduction was as a pest, but since then I have found native hollies in the southeastern USA and have come to appreciate the family a lot more since. In fact, I just ordered my first batch of Yaupon tea (poorly named Ilex vomitoria) just a few days ago.

Common Botanical Description

If you’re new to plant morphology, this guide is a perfect beginner’s description to learn how to identify the Aquifoliaceae family, with no need to know any scientific jargon. Below this section is additional information on uses and morphology photos to help you identify the family, followed by pictures of individual species found in North America. But for researchers or those wanting to learn a more in-depth version, refer to the Scientific Botanical Description below the images for highly detailed scientific descriptions and genus-level distribution data.

Leaves and Stems of the Aquifoliaceae: These are a family of shrubs and trees, mostly evergreen, sometimes deciduous, and are easily recognized when they have their characteristic spiny-tipped leathery leaves, but sometimes the leaves can be dull, softer and thinner, or have smooth margins. Leaves are simple (not compound) and are arranged alternately along the stem, rarely in opposite pairs.

Flowers of the Aquifoliaceae: Flowers are male or female on separate plants (dioecious). The calyx and corolla are partially fused at the base with 4-8 lobes each, and the flowers are mostly white or cream but may be greenish-white or rarely yellow, pink, or red.

Reproductive Features of the Aquifoliaceae: There are infertile stamens (staminodes) in female flowers and infertile ovaries in male flowers. Otherwise, male flowers have stamens that alternate with the petals, and female flowers have a superior ovary that sits above the petal attachment point, with a stigma (the surface that catches pollen from other flowers) on top but rarely has a style (thread-like structure that holds the stigma).

Fruits of the Aquifoliaceae: The fruits are always fleshy red, brown, black, or green drupes (like a cherry, but smaller and less fleshy).

Uses of Aquifoliaceae 

The Aquifoliaceae family is widely used as ornamental trees and shrubs in landscaping for their usually glossy, evergreen leaves, especially those with red berry-like drupes, which are routinely used for holiday decorations. Several members are also used as a caffeine-rich tea and coffee alternative (e.g., Yaupon and Yerba Mate from North and South America, respectively). The wood is also used for carving and specialty woodworking, and the leaves are used medicinally in TCM and indigenous cultures.

Wildlife and Ecological Values of the Aquifoliaceae

The Aquifoliaceae are woody shrubs and small trees mostly with evergreen leaves that provide critical year-round structure and habitat for countless invertebrates, birds, and small mammals. The berry-like fruits are also an important food source for many birds and small animals in the winter when foods are scarce.

Morphology of Aquifoliaceae in North America

Some Species of Aquifoliaceae Found in North America

Ilex aquifolium—English Holly

English holly has the typical shiny green leathery leaves with spiny margins, white flowers, and red berry-like drupes and is widely used in holiday decorations and landscaping. It has become invasive, even able to invade forest canopies through bird droppings filled with its seeds, like this young plant in a forest in BC, Canada.

Ilex cornuta—Chinese Holly

Chinese holly is an evergreen shrub reaching up to about 3 m tall with leaves that are usually 5 (or 4)-spined and 3.5 to 10 cm long and large red berry-like drupes. It is popular for landscaping because of its leaves, drupes, and tolerance of a wide range of conditions. This, however, has resulted in it becoming invasive in the United States, especially in the southeastern states where several beautiful native hollies already grow.

Ilex decidua—Possumhaw

This species is unique because it is deciduous, shown here with its bright red, berry-like drupes without leaves in late winter. It is an erect shrub, often with many thin trunks growing in a clump. Outside of its deciduous leaves, it can also be identified by leaves with crenate margins. While the birds love the fruits, they don’t eat them until they have frozen and thawed which removes some of the bitterness. It is native to the southeastern United states and northeastern Mexico.

Ilex opaca—American Holly

This medium-sized tree has light gray bark with small warty lumps and evergreen spiny-margined leaves that are often a lighter and/or duller green than other hollies; this one has the more rare yellowish flowers not often seen in the Aquifoliaceae. American holly is a US endemic native to the southeastern United States.

Ilex vomitoria—Yaupon Holly

Yaupon holly is an evergreen shrub growing up to about 9 m tall at most, with smooth light gray bark. It has evergreen leaves that are ovate to elliptical with crenate (rounded-toothed) margins instead of spines. It is an excellent source of caffeine and theobromine and was widely used as tea before the importation of Asian teas but is now gaining popularity again for its flavor and health benefits. It is native to southeastern North America, mostly the far southeastern United States, but also southeastern Mexico.

Scientific Botanical Description of the Aquifoliaceae Family

Habit & Leaf Form of the Aquifoliaceae Family

The Aquifoliaceae comprise a single Ilex genus made of shrubs and trees that are mostly evergreen or rarely deciduous. Leaves are always simple and almost always petiolate and alternately arranged but rarely may be opposite or sessile. They are often leathery but may be papery or membranous. The margins are often uniquely spinose and are rarely entire or serrated but may have varying margins even on the same plant at times; surfaces are mostly hairless. Stipules are often dark and may be minute, persistent, or caducous.

Flowers of the Aquifoliaceae Family

Plants are dioecious with axillary inflorescences that are in cymes with order 1, 2, or 3(-5) branching patterns with up to 1, 3, or 7(-31) flowers, with solitary on 1st-year branches and fasciculate on 2nd year.

Flowers are 4-6(-23)-merous, small, regular, hypogynous, and unisexual with abortive ovaries (M) or stamens (F), but they may occasionally be perfect and facultatively dioecious. The 4-8-lobed calyx persists in fruit, and the corolla is white, cream, or greenish-white, but rarely it can also be yellow, pink, or red with 4-8 imbricate petals that are connate for about 1/2 their length.

Male Flowers and Androecium of the Aquifoliaceae Family

Male flowers’ stamens alternate with petals and are epipetalous. Anthers are oblong–ovoid, introrse, and longitudinally dehiscent. The ovary is rudimentary, subglobose or pulvinate, and rostrate.

Female Flowers and Gynoecium of the Aquifoliaceae Family

Female flowers have sagittate or cordate, isomerous, epipetalous staminodes alternating with the petals and a superior, ovoid, 4-8(-10)-loculed ovary, mostly glabrous and rarely pubescent. The style is rarely developed, and it has a capitate, discoid, or columnar stigma. There are 1-2 ovules in each carpel, attached pendulously.

Fruit of the Aquifoliaceae Family

The fruit is a fleshy drupe, usually with as many stones as there are carpels, or fewer by abortion. They are usually globose or nearly so, in red, brown, black, or rarely green when mature, with 4-6 (1-23) pyrenes with a smooth, leathery, woody, stony, striated, rugose, or pitted endocarp. The seed has copious fleshy endosperm.

Taxonomy of Aquifoliaceae

The Aquifoliaceae is a small family comprising a single genus (Ilex) but with approximately 596 species in the small Aquifoliales order of the core eudicots. The Ilex genus is known to hybridize extensively, with some hybrid populations persisting and spreading.

Genera of the Aquifoliaceae:

Ilex (571).

Key Differences From Similar Families

The Phyllonomaceae and Helwingiaceae are related families in the Aquifoliales order made of shrubs and small trees, but they both have epiphyllous inflorescences (fasciculate in Helwingiaceae) on the upper leaf surface (towards the tip in Phyllonomaceae). They also have minute stipules in Phyllonomaceae and small fimbriate stipules in Helwingiaceae.

The leaves are sometimes confused with Mahonia spp. of the Berberidaceae, but that genus has pinnately compound leaves that are usually duller rather than shiny, and they produce yellow flowers instead of white or greenish in Ilex as opposed to simple and alternate in Aquifoliaceae.

Distribution of Aquifoliaceae

The Aquifoliaceae family is found on all continents except Antarctica, although it would not be considered cosmopolitan. It is most widespread in South America and Southeast Asia-Malesia. In Africa, we see fewer species and more limited ranges (2 species, mostly eastern), and in Europe, we see 3 species, which are western and southern.

Distribution of Aquifoliaceae in the Americas

Ilex species have a high center of diversity in South America, and their distributions throughout the tropics and subtropics are still fairly uncertain, which is why neotropical and Mexican genera are written as broad ranges rather than approximate species numbers.

Canadian Genera Include:

Ilex 5 spp. plus 1 hybrid; 3 spp. are native in ON, QC, and the maritime provinces (exc. Labrador); 1 sp. and 1 hybrid are introduced in BC.

USA Genera Include:

Ilex ~38 spp. plus 1 hybrid are listed as both native and introduced to most of the western half of the country, plus in the Pacific coastal states and HI.

Mexico Genera Include:

Ilex 130-150 spp. are found throughout all of Mexico.

Neotropical Genera Include:

Ilex 220-300 spp. are found throughout Central America and all of northern to central South America, excluding northern Chile.

Patagonia Genera Include:

Absent from southern Chile and southern Argentina.

Additional Information and References

• Visit Lyrae’s Dictionary of Botanical Terms to learn the terminology of botanists. Note that if you hover over most of the words in the articles, you can also get definitions from them there.
• Willis, Lyrae (Unpublished). Plant Families of North America. This is where all of the family descriptions come from. Below should be most of my references for this, along with my own personal observations throughout North America.
• Canadensys: Acadia University, Université de Montréal Biodiversity Centre, University of Toronto Mississauga, University of British Columbia. http://data.canadensys.net/explorer (accessed 2020 – current)
• FNA (1993+). Flora of North America. https://floranorthamerica.org/Main_Page. Accessed 2022-current.
• GBIF.org (2020+), GBIF Home Page. Available from: https://www.gbif.org
• iNaturalist.org (2020+). https://www.inaturalist.org/. Accessed 2020-current.
• Naturalista: CONABIO http://www.naturalista.mx (Accessed 2020–current).
• Neotropikey: Milliken, W., Klitgård, B., & Baracat, A. eds. (2009+). Neotropikey: Interactive key and information resources for flowering plants of the Neotropics. www.kew.org/neotropikey.com (accessed 2020 – current).
• Patagonia Wildflowers: Wildflower Identification Site. https://patagoniawildflowers.org/ Accessed throughout the fall of 2020.
• POWO (2019+). Plants of the World Online. Facilitated by the Royal Botanic Gardens, Kew. Published on the Internet: http://www.plantsoftheworldonline.org/
• Stevens, P. F. (2001+). Angiosperm Phylogeny Website. Version 14, July 2017 [more or less continuously updated since]. http://www.mobot.org/MOBOT/research/APweb/
• USDA, NRCS. 2020. The PLANTS Database (http://plants.usda.gov, 2 June 2020). National Plant Data Team, Greensboro, NC, USA; Accessed 2020-present.
• Watson, L., and Dallwitz, M.J. (1992+). The Families of Flowering Plants: descriptions, illustrations, identification, and information retrieval. Version: 2nd May 2020. delta-intkey.com. Accessed spring through fall of 2020.
• WFO (2022): World Flora Online. Published on the Internet: http://www.worldfloraonline.org. Accessed Spring 2022 – current

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I am currently seeking funding to expand my website and SEO capabilities as I keep adding new families, and I am also looking to invest in a new macro lens, as I will soon be adding floral dissections to the families as they become available to me. You can donate to help support native plant education using the GoFundMe link, also at the bottom of the page.

Copyright Information

The information and the photos on this site are free to use for educational purposes, with proper attribution. For other uses, please contact me first.

You can cite this site as follows: Willis, Lyrae (2020+). Lyrae’s Nature Blog – Plant Families of North America. https://lyraenatureblog.com/. Accessed [Enter Date].