Form and Function

Madia gracilis is a native plant that is found throughout the Pacific Northwest of the United States. It is commonly known as either Slender or Grassy Tarweed (Ross 2012). M. gracilis has some specific characteristics that set it apart from many of the other plants in its surrounding area. The plant itself grows anywhere from 4-40 inches in height, which can assist this plant in collecting sunlight and attracting pollinators (Ross 2012). Looking at M. gracilis you will notice that they have thin stems that are covered with many hairs (Turner 2013). At the top of these stems you will notice flowers that when bloomed release bright yellow petals that make it daisy-like in appearance (Ross 2012).  Also, M. gracilis has been described as an aromatic plant, meaning it has a distinct smell (Ross 2012). The smell given off by. M. gracilis is described as being strong and ill scented (Lowry 2009). Image: Madia gracilis flower and stem. Photographed by Dennis Ancinec. Used by permission.

One characteristic found in many Madia species is the use of glandular trichomes to help protect the plant from herbivores (Krimmel and Pearse 2013). The glandular trichomes secrete a sticky substance that covers the outside of Madia species, when herbivore insects land on the plant they get stuck (Krimmel and Pearse 2013).  This sticky substance explains why these species are considered Tarweeds.

Significant to many Madia species is that they are specifically adapted to grow in the dry, hot climates in the summer of the Pacific Northwest (Strong and Chester 2000). These species sprout in the spring, but do not flower till mid-late summer (Krimmel and Pearse 2013), this lateness has caused these plants to be known as “late bloomers” (Strong and Chester 2000). Because Madia species bloom late, most of the other flowers of the have already bloomed and dried up under the summer heat. With most other plants already bloomed and dried up Madia species have little competition for pollinators, water, and other soil nutrients (Strong and Chester 2000).  The sticky substance that covers Madia species is also helpful with the prevention of water loss (Strong and Chester 2000), similar to the cuticle that is found on Hepatophyta.

Image. Madia gracilis stem and flower. Photographed by Dennis Ancinec. Used by permission. The majority of the nutrients gained are taken up through the root structures. Madia gracilis has a mixture of a developed tap root and a complex system of fine root hairs (Antos and Halpern 1997). Because of this mixture, the plant is able to absorb all of the nutrients close to the earth’s surface, as well as shooting down enough to absorb water from deep down in the typically sandy soil. This shallow, widespread root system also explains other characteristics of the M. gracilis. Shallow root systems allow for rapid uptake of water and minerals that are close to the earth’s surface. Many of the regions that the M. gracilis lives in are prone to drought in the later parts of the summer, so this root system allows for the plant to absorb as much water as it can in the early part of the growing season so the seeds can be produced before the plant is exposed to unlivable conditions (Antos and Halpern 1997).

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