Arctostaphylos: A Wonderful and Confusing Genus

Arctostaphylos pallida bearing lush, green foliage, not shown is a beautifully twisting trunk. Photo by Native Here Nursery

Walking through the wrought-iron gates of the UC Botanical Garden fills me with excitement. It’s a warm, sunny October day, and a gentle breeze rustles the elegantly drooping needles of a relatively uncommon Montezuma pine (Pinus montezumae). However, I haven’t come here to see the unusual conifers; I’m heading straight to the California collection for the manzanitas! 

Now, if you’re anything like me, seeing the features of  Arctostaphylos thrills you. Muscular, twisting, smooth trunks and beautiful red-brown peeling bark contrasts strikingly with green to near white leaves. They range in form from imposing trees to creeping mats less than a foot tall at maturity. When springtime comes, beautiful white-pink flowers are borne in clusters that resemble tiny paper lanterns. Now, circling back to being like me, you may find yourself struggling to tell them apart!

There are around 90 species of manzanita; mostly native to California with some ranging from British Columbia to Northern Mexico. Unfortunately for us, many of them share extremely similar characteristics, often making identification difficult, but here are some tips I’ve learned to make it easier. 

First of all;  location, location, location! Sometimes, an ID can be narrowed down simply by considering the geographic range of the contending species. For example, the Santa Cruz Manzanita (Arctostaphylos andersonii) is nearly identical to the Pajaro Manzanita (Arctostaphylos pajaroensis), but the former occurs north of Santa Cruz, while the latter occurs south. 

Arctostaphylos pajaroensis ‘Myrtle Wolf’, a selection with captivating bright pink blooms. Photo by me, taken at UC Botanical Garden, Berkeley

Then, there are small details of leaf characteristics, like a coating of fine hairs, a lack thereof, or a blue tint. (Or, in botanical lingo, “tomentose, glabrous, and glaucous”). Sausal Creek’s very own manzanita species is a perfect example for this next comparison; the Pallid Manzanita (Arctostaphylos pallida) also bears a very prominent resemblance to the Pajaro Manzanita, and deservedly so, as both species share a chromosome count of 26. But, with a closer examination of the leaves, we can easily see that the Pallid Manzanita’s style is truly of her own design. Her leaves are abaxially dull blue-green (the stem-facing side of the leaf, or the lower side), while the leaves of the Pajaro Manzanita are abaxially light green.

Additionally, the leaves of A. pajaroensis are slightly cupped, while the leaves of A. pallida are flat. And, if you catch it in fruit, notice that the berries of A. pallida are quite sticky, unlike its Pajaronian  cousin. Or, if caught in flower, take note of any inflorescences with only two individual flowers, a characteristic of A. pajaroensis but not A. pallida.

If all else fails, find the nearest park ranger, docent, or volunteer; they will likely be very familiar with the Arctostaphylos species in that area and botanically passionate enough to talk to a random person about them in great detail. Seize this opportunity for knowledge!

In conclusion, I hope this guide can be a helpful resource for anyone like me who struggles to differentiate manzanitas. Every species has its own unique beauty, sometimes we just have to look closer to see it.

By Oliver Hopkins, FOSC Student Board Member