Reiman's Picks

Catalpa speciosa

Reiman’s Pick
For the Week of August 3, 2009

Catalpa speciosa: Northern Catalpa, Cigar Tree or Indian-bean

Kyler Sheets
Outdoor Horticulture Intern
Reiman Gardens, Iowa State University

The name Catalpa originates from the word Catawba, the name of a southeastern Native American tribe.  Botanist Giovanni Antonio Scopoli accidentally coined the scientific name for this tree, Catalpa, instead of Catawba due to a transcription error.  According to the rules of botanical naming, the first spelling of the formal scientific description has to remain the scientific name and this name stands today.

The common name of the Catalpa is the Cigar Tree, from the bean-like pods that are present in autumn.  A highly underused wood, the Catalpa has the lowest shrinkage and expansion rate of any domestic hardwood and has been used to make totem poles, canoes, furniture, interior trim and cabinetry.    Being the primary source of food for the Catalpa Sphinx moth (Ceratomia catalpae) some anglers plant these trees around private ponds and use the “catawba-worms” as live bait.

Northern Catalpa (Catalpa speciosa) is a 75-100 ft tall deciduous tree.  Belonging to the Bignoniaceae family, the Northern Catalpa is closely related to the Trumpet Creeper vine.  It has grayish to reddish-brown bark that forms thick scales.  The large heart-shaped leaves of this plant are about 12 inches long to eight-inches wide with eight-inch long petioles.  The Northern Catalpa blooms in clusters of showy two-inch white bell-shaped flowers with yellow streaks and purple spots inside the petals.  The fruit is a bean-like pod with many small flat seeds inside.  Each seed has two thin wings for wind dispersal. The pods grow up to 18 inches in length and about half an inch in width.  Persisting through winter, some say these pods resemble brown icicles.

The Northern Catalpa is winter hardy in Iowa, but is native from Illinois and Indiana south to Arkansas and Tennessee.  This tree can grow in most of Northern America, but it does best in moist, high pH, coarse to medium textured soils in full sun.  Northern Catalpa does not tolerate shade, but they seem to tolerate some drought.  These trees are widely grown for the ornamental value and long lifespan. Being one of the last trees to put on foliage in the spring they provide much needed shade and weather protection for our feathered friends.

To experience the beautiful flowers of the Northern Catalpa, visit a grouping at the end of June at Iowa State University’s Reiman Gardens.  You’ll find them due east of the Mahlstede Building.  And while you are there - take some time to smell the roses.

Quaking Aspen

Reiman’s Pick
For the week of July 27, 2009

Quaking Aspen

Jacqueline Kolpek, Outdoor Horticulture Intern
Reiman Gardens, Iowa State University

Dating back to the Ice Age, the Quaking Aspen Populus tremuloides, spread from Canada throughout the United States and became a beautiful addition to the landscape.  The rustling of its leaves in the wind creates a unique, soft sound and its namesake quality.   Native Americans referred to this aspen as “woman’s tongue”.  The women would recreate this sound at many important events such as ceremonies, weddings, funerals and tribe gatherings.

Today, Quaking Aspens are one of the most widely dispersed trees across the nation; however, many people are unfamiliar to their unique characteristics. The existence of Quaking Aspen in the Western United States creates a beautiful landscape within the mountains of Colorado and Utah. The Aspen is an upright, deciduous tree that stands at an average of 40-100 feet tall with a spectacular smooth white trunk of one to two feet in diameter. The leaves are eye-catching as a slightly heart-shaped, almost perfectly rounded leaf one to three inches long. These flat leaves have a dark green color above and a pale green color underneath which change from yellow-orange, gold, to red during the fall. Quaking Aspens tolerate many different living conditions from full sun to cold temperatures; soils rich in clay to moist loams. A unique characteristic of the Quaking Aspen is their tolerance to fire. It has adapted by having little heat resistance in its thin bark, but with a root system that rapidly creates numerous sprouts after fires to produce new trees.

The wood of the Quaking Aspen can be used in many different ways. Because of its fine, uniformed texture, the wood is able to withstand applications of glue and paint. Its high resistance to splitting makes it very useful as pulp products such as particleboard, chipboard, insulation board and specialty papers for newsprint and books. Over the years, there are many commercial uses that have put quaking Aspen in higher demand such as animal bedding, matchsticks, toys, tongue depressors and ice cream sticks.

Now is the perfect time to admire the Quaking Aspen. Come experience the beauty and unique flutter of leaves on Quaking Aspens found throughout Reiman Gardens.

A Living Fossil: Ginkgo biloba

Reiman’s Pick

A Living Fossil: Ginkgo biloba

Elizabeth Childs, Reiman Gardens

What is a million year old fossil doing in the Conservatory at Reiman Gardens?  Growing, of course!  Ginkgo biloba, sometimes referred to as the maidenhair tree, is a living fossil, with fossil relatives dating back to more than 200 million years ago.  This prehistoric plant is the only living member of the family Ginkgoaceae, which survived under the protection of Chinese monks, long after its few relatives had gone extinct.
 
This elegant tree can reach heights up to 100 feet and has an upright form.  Fancy, smooth, two-lobed leaves decorate the tree, giving it the name biloba.  Ginkgo trees are gymnosperms and do not flower or produce fruit.  However, females still produce seeds that are partially covered in a fleshy skin and can be quite messy in a landscape, plus have a foul odor. When possible a male tree or named cultivar should be selected. Ginkgo trees are referred to as either “male” or “female” because of the male and female flowers on separate trees. The ginkgo leaves turn a nice golden yellow in the autumn before falling for the winter.
 
Ginkgo trees are hardy in zones 3 to 9.  Once native to the northern hemisphere, ginkgos are well adapted to Iowa conditions being both wind and salt tolerant plus drought-resistant.
 
Available Ginkgo biloba cultivars provide excellent trees for the landscape.  Along with its excellent tolerances mentioned above, it is an attractive tree in a landscape; just remember 100 foot trees require room to grow.  This tree is quite adaptable and appropriate for many locations such as yards, parks, street sides, and gardens.
 
There are many examples of ginkgos growing at Reiman Gardens. Explore ginkgos in the Gardens’ permanent collections or view them nestled in among the tropical plants and other living fossils of the Conservatory before the Landscape Before Time display goes extinct!