Saturday, October 12, 2013

Acorn season

I am collecting acorns from Engelmann oaks here in South Pasadena. Engelmanns, also known as Pasadena or mesa oaks, are not only rare and unusual, but magnificent as well. When mature they have a broad crown with spreading, horizontal branches so massive that it is hard to imagine how they can hold themselves up.

It is believed that these amazing trees once occupied a range from the Pacific Ocean in southern California east to Arizona. Uplift and subsequent drying that resulted in the formation of the Sonoran and Mojave deserts left remnant populations of these trees in the counties of  San Diego, Los Angeles, Riverside and Orange. If you have not been to the Santa Rosa Plateau Ecological Reserve in Riverside County you are missing something very, very special! I visited about a year ago and was so taken that I posted some pictures on this blog. There is also an unusual collection of Engelmann oaks at the LA Arboretum.

The Engelmann oak may be the rarest, most at-risk oak due to its limited range and the fact that this range is located in such a high population area. Here in South Pasadena there are quite a few old Engelmanns that pre-date development. It seems that each year a few more die, possibly due to landscaping practices, drought or other adverse conditions. These oaks are usually growing in someone's lawn or garden, but unlike the coast live oak, these seedlings rarely take hold to replace the mature Engelmann oaks.

The Arroyo Seco Foundation and Rancho Santa Ana Botanic Garden collect and propagate acorns from these vulnerable oaks. I have collected from South Pas's trees and brought bags of acorns to both organizations, as I will again this year.

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Acorns collected from different Engelmann oaks in South Pasadena. Notice how variable they are. Some are longer,
others are rounded and quite large, and still others are significantly more petite, some are ridged on the
outside while others are very smooth.
For more information on our wonderful and unique oak, check out the following links:
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Seedling protected from
predation with chicken
wire (LA Arboretum)


Better yet, walk the streets of South Pasadena, Sierra Madre, Pasadena and Alhambra looking for these  extraordinary giants. Collect some acorns and try sprouting them yourself. The acorns must be sprouted immediately, though you can keep them for a short time in the refrigerator. Place them on the top of the soil, either in a deep pot or in the garden, with a light covering of soil. Acorns from Engelmann oaks do not have to be buried, though they should be kept moist as they start growing. Many seedlings and saplings are lost either from lack of moisture or predation by rodents, so you may have more success starting them in a container. The container must be deep since they do put down a deep tap root after germinating.

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Though acorns from Engelmann oaks vary greatly in size and shape, all have rounded tips
(in contrast to the pointed tips of the usually longer and thinner coast live oak acorns, see below). 
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Majestic Engelmann oak in front of an apartment in Pasadena. 
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Engelmann oak at LA Arboretum
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Engelmann oak (right) growing with coast live oaks (left) at Santa Rosa Plateau Ecological Reserve
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Large Engelmann oak, possibly a hybrid, in South Pasadena
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Lovely Engelmann oaks growing in front of two South Pasadena homes.
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Brownies from local troop plant acorns from mature coast live oak trees in the South Pasadena
nature park. They collected them from trees in the park that probably pre-date development. 
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Coast live oak seedling
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Coast live oak acorn, note pointy tip, in contrast
to the rounded tip of the Engelmann oak acorn
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Coast live oak in South Pas nature park.

6 comments:

Linda Prince said...

Excellent! When I saw the title I thought it might be an ethnobotanical piece on acorns. I should have known. Thanks for assisting this wonderful oak.

Mike Letteriello said...

If we ever get permission to tear up
some more blacktop at Prisk Native Garden, I'd certainly be interested in planting some Engelemann oaks as part of a new greenbelt to the freeway
on the playground.

Anonymous said...

WONDERFUL WONDERFUL!

Planted my school's first new Coast Live Oak seedling . . . the Englemann is awaiting final site prep this week.

Leigh said...

It is really gratifying to see these oaks being appreciated and enrolling children in the gathering and planting of the acorns. Well done!

Amy Nettleton said...

Thanks for this great piece... and for your good work. Recently I have been appreciating the Engelmann oaks that grow in Big Santa Anita canyon (above Arcadia). You see evidence of them first on the trails, where their acorns, and often just the caps, practically pave the ground. Some acorns are big enough that you could almost trip on them. The most remarkable ones have the beautiful deep burgundy brown color that shows on some that you have collected.

Raphael said...

I'm experimenting with some scrub oak acorns I collected near Agua Tibia. The brown ones I collected were all rotten inside, so I'm trying my luck with the greenish ones. You think that's got any chance of success?