UC Davis Arboretum Acacia Grove in full bloom

The Eric E. Conn Acacia Grove at the UC Davis Arboretum has one of—if not the—most significant collections of acacias in Northern California. From the Arboretum website:

The Eric E. Conn Acacia Grove displays over 50 species of acacias from Australia, Africa, and the Americas. In early spring, visitors can walk through clouds of fragrant yellow blossoms amid meadows of native California bunchgrasses. We are testing these attractive heat- and drought-tolerant plants, which range from prostrate, low-growing species to tall shade trees, for use in Central Valley gardens. The grove is named for Dr. Eric E. Conn, professor emeritus of biochemistry at UC Davis and an internationally-recognized expert on acacias.

In the past, the collection had a larger number of acacias from the Americas and Africa but since they tend to be frost-sensitive, many of them have died. As a consequence, today’s collection is heaviest on Australian species, most of which go by the moniker “wattle.” (The word comes from wattle and daub, a traditional building method that has been around for thousands of year.)

I think acacias are attractive trees right round. However, when they bloom in February and March, they stop traffic—not only because of the masses of yellow or cream-colored flowers, but also because of the heady fragrance. It’s hard to describe: sweet, a bit like honey, a bit spicy. A couple of species, Acacia dealbata and Vachellia farnesiana, are even used in perfume production.

At this time of year, you can see and smell the acacias at the UC Davis Arboretum even before you get to the Acacia Grove. It’s one of the most magnificent spectacles the Arboretum has to offer.

When I joined a walk through the Acacia Grove a couple of years ago, the docent explained that American and African acacias are closest to the mimosas from which they are thought to have originated. Their leaves still look like the typical mimosa leaves while many Australian species have evolved in a different direction, with leaves that are often radically different from the typical mimosa leaf. In fact, many Australian species, such as Acacia pravissima, have phyllodes (modified flat leaf-like structures that are actually modified stems) instead of traditional leaves.

Until 2005, the genus Acacia contained about 1300 species: 960 from Australia, the rest from warm-climate areas in Europe, Africa, southern Asia and the Americas. In 2005, in a contentious move that caused a tremendous amount of bad blood among taxonomists, the genus Acacia was split into five separate genera. The Australian and Asian species retained the original genus name while the others were reclassified into four new genera: Vachelia, Senegalia, Acaciella and Mariosousa.

Not that most regular folks are affected by taxonomical shenanigans of that sort. Even nurseries don’t seem to be too eager to jump on the bandwagon. The palo blanco I just planted in the front yard, an acacia from northern Mexico, was still labeled Acacia willardiana even though it became Mariosousa willardiana over 10 years ago.

Leaving all that aside, let’s take a look at the acacias that are in bloom right now at the Eric E. Conn Acacia Grove:

Brisbane golden wattle (Acacia fimbriata)

Brisbane golden wattle (Acacia fimbriata)

Hairy wattle (Acacia vestita)

 

Hairy wattle (Acacia vestita)

Knife-leaf wattle (Acacia cultriformis)

Knife-leaf wattle (Acacia cultriformis)

Knife-leaf wattle (Acacia cultriformis)

Ovens wattle (Acacia pravissima)

Ovens wattle (Acacia pravissima)

Ovens wattle (Acacia pravissima)

Ovens wattle (Acacia pravissima)

LEFT: Weeping myall (Acacia pendula)  RIGHT: Silver wattle (Acacia dealbata)

LEFT: Weeping myall (Acacia pendula)  RIGHT: Silver wattle (Acacia dealbata)

Shoestring acacia (Acacia stenophylla)

Red-leaf wattle (Acacia rubida)

Red-leaf wattle (Acacia rubida)

Silver wattle (Acacia dealbata)

Silver wattle (Acacia dealbata)

Silver wattle (Acacia dealbata)

Silver wattle (Acacia dealbata)

Silver wattle (Acacia dealbata)

Silver wattle (Acacia dealbata)

Silver wattle (Acacia dealbata)

Mudgee wattle (Acacia spectabilis)

Mudgee wattle (Acacia spectabilis)

Snowy River wattle (Acacia boormanii)

Snowy River wattle (Acacia boormanii)

Snowy River wattle (Acacia boormanii)

Snowy River wattle (Acacia boormanii)

Snowy River wattle (Acacia boormanii)

Snowy River wattle (Acacia boormanii)

Snowy River wattle (Acacia boormanii)

Blue bush (Acacia covenyi)

Blue bush (Acacia covenyi)

Varnish wattle (Acacia verniciflua)

Varnish wattle (Acacia verniciflua)

Varnish wattle (Acacia verniciflua)

Silver wattle (Acacia dealbata)

Silver wattle (Acacia dealbata)

Silver wattle (Acacia dealbata)

Queensland silver wattle or pearl acacia (Acacia podalyriifolia)

Queensland silver wattle or pearl acacia (Acacia podalyriifolia)

Queensland silver wattle or pearl acacia (Acacia podalyriifolia)

Queensland silver wattle or pearl acacia (Acacia podalyriifolia)

Queensland silver wattle or pearl acacia (Acacia podalyriifolia)

Queensland silver wattle or pearl acacia (Acacia podalyriifolia)

Queensland silver wattle or pearl acacia (Acacia podalyriifolia)

If you have the opportunity to visit, the best place to park is at the new Putah Creek Lodge parking lot off Garod Drive (use this link for Google Maps directions). Parking is $9 during the week; free on the weekend. Walk to the east end of the parking lot, cross the foot bridge across Putah Creek to Putah Creek Lodge, take a left on the walking path and continue straight for about 1/4 mile.