Tuesday, November 18, 2008

Going to Seed: Acorns

Reproduction is important in plants just as it is in animals. In both, when the mature generation is aging, a new generation needs to be growing up to take its place. In many plants, such as wildflowers, trees and shrubs, seeds are produced from fertilized flowers, and they carry the spark of life that will become the new generation, and they are often packaged with the food that will give them a good start.

The seeds of oaks trees are acorns. The acorn is defined in the book, "Plant Identification Terminology" by James G. Harris and Melinda Woolf Harris as," The hard, dry, indehiscent (which means that they do not open at maturity along definite lines) fruit of oaks, with a single large seed and a cup-like base".

According to an excellent book about the use of plants by animals of the U.S., "American Wildlife and Plants, A Guide to Wildlife Food Habits" by Alexander C. Martin, H. S. Zim and A. L. Nelson, "Oak trees are of major importance to both man and wildlife, and acorns are at a position at, or very near the top of the wildlife food list. Acorns provide a good and abundantly available staple - the staff of life for many wildlife species. The acorns of the white oak species are more palatable to wildlife just as they were preferred by the Indians and early settlers." The red oaks are much higher in tannins which makes their acorns bitter.

I don't know where this illustration of different seeds types "Common Types of Fruits and Seeds" came from, but we have used it for years with students and at workshops. The acorn is in the upper left-hand corner. (If you know the origin of this illustration , please let me know so I can give the author and/or artist credit.)

Bur Oak has very large acorns (Quercus macrocarpa) ["macro" = large "carpo" = Greek for fruit] and the Bur Oak tree's acorns are the largest we have at the ranch. This one is over an inch wide and if you count the cup which is deep and fringed with course hairs in the measure it is almost 2 inches wide . The leaves of the Bur Oak can be up to a foot long. The leaves in this picture were 6 to 9 inches long.

The Bur Oak acorns on the left are huge compared to the much smaller Spanish Oak (Quercus buckleyi) acorns on the right (note the quarter in the middle of the large acorns for size comparison). The white oak family to which the Bur oak belongs are sweet. Red oak acorns are high in tannins which give them a bitter taste. Native Americans made flour and tasty dishes with white oak acorns. Animals love them too.

Bur Oak Acorns are very popular with animals. These acorns have been partially eaten, probably by squirrels. J David planted Bur acorns in pots by the Greenhouse, and covered them so no acorn loving critters couldn't reach them. He underestimated the cunning of squirrels, and was dismayed when he returned to find that eight of the containers showed evidence of tampering. Two of them still had an acorn and in the others the acorns were missing.

These beautiful dark brown acorns are on a Plateau Live Oak tree (Quercus fusiformis) and are up to an inch long. The large number of Plateau Live Oak trees in this area mean that their acorns are important food for turkeys, deer, jays, titmice and woodpeckers. It is also the host plant for the caterpillars of skippers, hairstreak and admiral butterflies.

Live Oaks can get to be very large. This one, along Miller Creek has a sign that says "Largest Oak Known in Blanco County". I have no idea whether it is a Plateau Live Oak which is the common oak here at the ranch, or if it is the Coastal Live Oak (Quercus virigiana). It is huge and I think very, very old.

These acorns were on the ground under a large Lacey Oak (Quercuw laceyi) tree. We have a grove of these beautiful oaks along Miller Creek. I didn't find any of the smaller trees with acorns on them, so I was unable to get a photograph of acorns in their cups on a tree.

The old Lacey Oak trees in the grove are beautiful, with light gray bark, and graceful arching branches.

The leaves of the Lacey Oak have a thin coat of a waxy substance on their surface that reduces water loss during dry spells, and also gives the tree a bluish tint which has earned this oak the common name "Blue Oak".

There are many animals that love acorns and some actually hide them away for later in the year when food is less plentiful. Squirrels and other small mammals bury them, and then forget where they put them. Thus they plant a new crop of oaks, and some of the new plants will replace the old ones that are dying. The young sprouts are also food for other animals.

I found out from Scott Grote, who manages the deer and hunts, that the acorn crop this year is large enough that the White-tail deer aren't as interested in our corn feeders as they are in years when the acorn crop is smaller.

There are many cycles in nature, warm and cold, wet and dry. It would seem that a dry year like this past 12 months would produce a small crop of acorns. However when you consider that we had an unusually wet spring in 2007, the extra water probably gave the oaks the health they needed to make it through a dry year. When looking at the health of trees you look at what has happened in the last 2 or 3 years, not just the recent seasons.

Enjoy the fall. Leaves are changing color. Lots of plants produce their fruit in the fall. The air is often cool. It is one of my favorite times of the year.

Of course, I would love to see some rain!


Anonymous said...

Thank you for identifying the Bur Oak for me, Margaret. I live in town in New Braunfels, and every year my grandson and I love hunting for these large acorns from a nearby church yard. Now I can tell him the correct name of the tree! I enjoy reading all of your posts. Thanks for all the great photos and information. Linda Dufour

Leslie said...


I think my grandma and grandpa knew you and J David years ago. I grew up on Greenwood Valley Ranch, not far from your ranch--we also had exotics. My grandparents were Jeff and Fernne Hunt. Let me know if you remember them.

Margaret Bamberger said...

Leslie and Linda.

Thank you both for your comments. I love hearing back from readers of the BRP Journal. Leslie, I asked J David if he knew your grandparents, and yes he remembers them. Greenwood Valley Ranch is in the area where he is working to delist the endangered Texas Snowbell. That is a beautiful area and you were lucky to grow up on such a magical place. Do you remember seeing the Texas Snowbells on a canyon wall near the creek/river?

The post published on December 14, is about a snowbell planting trip near Dolan Falls, and you might find interesting.

Steven Fulton, our ranch biologist is doing research for his masters degree on the plants at Eagle Ranch (next to Greenwood Valley Ranch I believe).

Thanks again, and I hope to hear many more comments from you both. Feel free to e-mail me at margaret@tstar.net or mbamberger74@gmail.com

burraakk said...

while surfing on net , i saw your blog..oak trees and and their fruits were so nice .. i think i ll be back later too and spend more time .

dama said...

HI, my name is Lin Andis, I am Leslie's mom, [Jeff & Ferne's daughter] I remember well the Texas Snowbells, I went with the group when they went to identify and collect seeds. I just completed the AAMN course and was lucky enough to talk to a lady that still has plants propagated from thoes few collections. It is good to remember old times, Thanks, Lin