Category: Trees (Page 6 of 17)

Seed of the Week: Chinese Elm

Our mystery seeds from last week came from a Chinese elm tree, Ulmus parvifolia.

Because most of our American elms were destroyed by Dutch elm disease, people have started planting Chinese elms, which as the name suggests are originally from Asia. It is much more resistant to the Dutch elm disease.

Chinese elms produce numerous winged seeds, technically samara, in the fall. The samara are dispersed by the wind when they mature.

The seeds readily germinate in the spring. First, the root emerges.

The seed coat slides off, exposing the green, round cotyledons.

If the seed is in a suitable place to grow, the cotyledons emerge from the soil. Between them the first two true leaves begin to grow.

The little trees are all ready to take off. We have Chinese elm seedlings everywhere!

The leaves are simple (not compound), with teeth around the edges.

The mature tree is often grown in parks here in Arizona. It has a pleasant fan-shaped crown, and the branches drape nicely.

The most striking feature of the Chinese elm tree is the mottled and peeling bark. It often shows orange underneath.

Unfortunately I had on the wrong lens, so this photograph isn’t the best presentation of the full-sized tree.

Because of their unusual bark, and also probably because they produce seedlings so easily, Chinese elms are often used for bonsai.

It will be interesting to see how the Chinese elms fare as landscape trees over time. They definitely have good qualities, and less desirable qualities, as well.

Have you ever seen a Chinese elm? What do you think of them?

Seed of the Week: Olives

You may have seen the mystery seeds from last week when you pitted an olive. The ones in the photo were lying on the ground under an olive tree, Olea europaea.

Olive trees are originally from the Mediterranean region, where much of the world’s olive oil production still occurs. In the United States, olives grow in California and Arizona.

Olives are small trees, sometimes with multiple trunks.

The trunks of older trees are often gnarled and twisted, giving the trees and interesting look.

The leaves are a lovely greyish-green.

The flowers are greenish-white and are pretty much inconspicuous. Olive pollen is a known allergen. Here in Arizona a sterile variety of olive (that doesn’t produce pollen) has been developed for those who simply want to use the tree for ornamental purposes.

The fruit of the olive is green to red at first…

Over time the fruit turn black and drop off the tree.

Many newcomers to Arizona see the olive fruit and wonder if they can eat them, but olives straight from the tree are not edible. The fruit needs to be leached in salt and vinegar and then processed before it is good to eat. Or the fruit can be processed into oil.

You can grow olives from the pits, but of course the new plants won’t necessarily resemble the parent tree. Botanists have tricks to weaken the hard pit and increase the chance of germination, such as gently cracking the surface.

All this talk about olives has made me hungry. Maybe it is time for an egg salad sandwich with olives.

Do you have a favorite way to eat olives?

Seed of the Week: Pecan

The mystery seed from last week was no mystery, it seems. Karen and Heather correctly identified it as a pecan as soon as it went live.

Did you know that pecans, Carya illinoinesis, are originally from North America, particularly the Mississippi River region? They are closely related to another of my North American favorites, the shagbark hickory, Carya ovata.

The parts we eat are called nuts, but most botanists agree they are the stone or pit of a drupe. The fruit forms within a green, fleshy husk.

Here in Arizona the fruit is still on the tree in its husk right now.

Over time the husk will dry and split open.

Then the mature pecan will drop to the ground.

Pecan trees have compound leaves, which means they are composed of small leaflets clustered together.

The trees are quite large, up to 70 feet tall, and are deciduous (drop their leaves in winter).

They make lovely landscape trees if you live in the areas where they will grow, although at least here in Arizona they are susceptible to an aphid that drips sticky honeydew at certain times of the year.

If you would like to grow a pecan from seed, keep the shell intact (like the first photograph). You may plant it in the fall. If not, then you will need to subject it to a period of cold that mimics a winter underground in order for the seed to germinate. The process is called “stratification.”

E-How has instructions for preparing a pecan for planting for kids.

Have you ever wondered how pecans are harvested? In this video you will see the three step process. First the pecans are shaken from the tree, then they are gathered into a pile or windrow, and finally they are gathered and sorted. The video is long, but the last machines are worth the wait.

Finally, what discussion of pecans is complete without a lovely pecan pie?

Photo credit: Stu Spivack

What is you favorite way to eat pecans?

For more information, try:

The North Carolina Pecan Growers have lesson plans and games.

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