Can’t see the flowers for the trees?

May 29, 2009 at 11:28 am 4 comments

By Philip Potyondy, University of Minnesota Extension

The giants and their tiny flowers

black locust blooming on Midtown Greenway in Minneapolis, MN

Black locust May 31st, 2009 Midtown Greenway in Minneapolis, MN

The scent of spring wafts into our nostrils and affirms spring is here.  Is that quinte-scent-ial smell rising from below our knees or is it falling from the heavens?  Maybe a little of both.  High above our heads in the tops of trees flourish a multitude of flowers.  This sounds a bit … well… flowery … but it is true.  In the tops of our colossal statuesque canopy forming titans are sprightly little flowers fit for a pixy.

“…And the flowers and the trees…”

The Birds and the Bees, Jewel Akens 1965

Red maple female flowers April 23, 2007 Brainerd, MN.  These showy red flowers are insect pollinated. (image by esagor)

Red maple female flowers April 23, 2007 Brainerd, MN. These showy red flowers are insect pollinated. (image by Eli Sagor)

One of the hallmarks of spring is when the crab apples and other fruit trees are in bloom.  In about the second week in May In the Longfellow neighborhood in south Minneapolis, many of the streets are lined with brightly colored and honey scented crab apple trees this time of year.  Without going too far down the botany lingo path of gymnosperm, angiosperm, carpel, and sporophylls with fused margins, consider that in order for trees to reproduce (make more trees) they’ve got to make a seed.  And before many trees, or any kind of plant, can make a seed it needs to make a flower.  And that flower needs to be pollinated.  The majority of flowers on trees are pollinated by the wind or by insects; a few are pollinated by hummingbirds.

The size, color and shape of a flower is linked to how it gets pollinated.  Wind pollinated trees depend on the wind to move a pollen grain from a male flower to a female flower. It is most effective for them to put energy into making a lot of flowers, pollen, and eventually a lot of seeds versus making a big colorful flower.  If a tree is trying to woo a specific insect to carry its pollen directly to another flower, it is a good use of plant energy to make a larger attractively colored flower.  It is also worth the plant’s energy to make enough pollen so that the friendly little bug gets a meal in exchange for courier services.  You can make a guess about how a flower is pollinated based on what the flower looks like.

American elm flower April 19, 2009 Minneapolis, MN.  The large bud in the upper left is less than an inch long and will eventually open as the leaves expand.  The flowers are wind pollinated.

American elm flower April 17, 2009 Minneapolis, MN. The large bud in the upper left is less than an inch long and will eventually open as the leaves expand. The flowers are wind pollinated.

Fresh cut flowers

By the time some of the more showy flowers bloom, like magnolias, crab apples and lilacs many of many less noticeable flowers have already bloomed in yards, in the woods and on boulevards.  Many of these flowers come out before the leaves.  One way to view and observe the more dainty specimens is to bring them into your home.

Prune off some approximately pencil thick branches off a tree in your yard.  Low hanging branches or water sprouts growing from a previous pruning cut are fine candidates for harvest since they will potentially be pruned soon.  You can display them, much like cut flowers from the florist, with water in a vase.  Place your piece of spring in a location you will see often, like where you eat breakfast.  American elm is a great tree to take a cutting from early in the spring.  Watch the buds early in the spring and collect a cutting just after you notice something starting to emerge from the buds.  The cutting on your table will develop and bloom at about the same rate as the flowers up in the tree’s canopy.  This is a great way to watch up-close how the flowers develop and change in a short amount of time.  Use a magnifying glass or hand lense to get an even better view.

American elm flowers April 19, 2009 Minneapolis, MN.  Freshly emerged winged fruit is called a samara.  Each samara holds one seed.  Seeds are wind dispersed using those wings to float in the slightest breeze.

American elm flowers April 19, 2009 Minneapolis, MN. Freshly emerged winged fruit is called a samara. Each samara holds one seed. Seeds are wind dispersed using those wings to float in the slightest breeze.

Pursuing petals

Viewing tree flowers, especially the smaller ones, is not as easy as noticing large brightly colored flowers.  It takes a bit more observation and focus but is rewarding.  It can be hard to see the details on branches of large trees.  Look for low hanging branches.  Yards and natural parks are good places to find branches that haven’t been pruned up too high for viewing.  One way to view details in the crown of a tree is to use binoculars.  You can view from the ground or even from an upper story window in your house.  Another use of the binoculars is to look through one of the lenses the wrong way to see the detail of a little flower up close.  You need to have the object you are viewing almost touching the glass on the small end and your eye on the big end.  The best way to notice when a tree is blooming or changing in some way is to look at trees that are part of your daily routine.  Glance at the tree or shrub nearest to your front door when you get home.  Check the tree at your bus stop when you arrive at work.  Trees are always changing and can be enjoyed through watching these subtleties.

Bur oak flowers and leaves May 13, 2009 St. Paul, MN.  These male flowers are known as catkins.  They are wind pollinated. (image by Eli Sagor)

Bur oak flowers and leaves May 13, 2009 St. Paul, MN. These male flowers are known as catkins. They are wind pollinated. (image by Eli Sagor)

Floral calendar

Seasonal changes in a plant, including blooming, is determined by a number of factors.  One way plants regulate when they bloom is by measuring the length of the night.  Plants are also impacted by temperature and other environment factors.  Botanists use growing degree days(GDD) to predict when a plant will bloom.  This system calculates blooming dates by measuring daily temperatures but variations in temperature from year to year make it difficult to put blooming times on a specific date on a calendar.  See the table below for approximate times to look for selected tree flowers.  If you are wondering about other species check out the resources below or simply keep a keen watch on your tree.

Enjoy discovering tree flowers.  This is a fine activity to do on your own, but better yet share your excitement with a friend, neighbor, or family member.

Share your favorite tree flowers and when you saw them blooming in the comment section below.

Further investigation

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Entry filed under: phenology. Tags: , , , , .

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4 Comments Add your own

  • 1. Lee Jofa  |  May 29, 2009 at 11:37 am

    great blog! i learned a lot

    losts of information on plants

    Reply
  • 2. Beth iflorist.co.uk  |  May 31, 2009 at 5:08 am

    Beautiful pictures and great blog. I learned a lot. Every time I come home after a garden tour I start getting new ideas for my own garden.

    Reply
    • 3. esagor  |  June 1, 2009 at 8:45 am

      Thanks Beth! I’m glad you enjoy the site.

      Reply
  • 4. Vicky  |  June 11, 2009 at 4:39 am

    Flowers are excellent in the process of developing the landscape of your front yard. It would be great if you ask for help from the professionals who are well experienced.

    Reply

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News and information of interest to Minnesota woodland owners. Sister site to MyMinnesotaWoods.org.

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