Goldenrod and Asters

Aster and goldenrod on the quarry wall

Goldenrod and asters are companionable plants at Halibut Point, finding their way into similar niches of many types. They are easy for Park visitors to recognize in a general way, particularly when in flower. They are the yellow ones and the blue ones of late summer.

Seaside goldenrod (Solidago sempervirens) and White heath aster (Symphyotrichum ericoides)

With a little closer look more distinctions of color and form appear, especially in the case of the asters. The blues vary from purple to white, the postures from tall to prostrate. The star shapes for which they are named show subtly different configurations. The leaves of various species range from broad to needle-like. Diversity abounds.

Flax-leaved aster (Ionactis linariifolia) and Downy goldenrod (Solidago puberula

The asters are multi-colored daisies. Their central button is actually a dense cluster of tiny disc flowers capable of producing seeds. Each disc flowers is ringed by five fused petals. A row of ray flowers encircles the button. Each ray flower extends a large strap-like petal outward. Collectively they make up the showy corolla. This composite ensemble comprises a bright and business-like inflorescence that attracts pollinators, children, and florists. The composite family may be the most widespread flowering plant group in the world.

With such great distribution the composites not surprisingly present a taxonomic wonderland to botanists, who currently recognize over 32,000 different species in 1,900 genera. All of these are distinguished by the daisy grouping of disc flowers, though not all combine them with large-petaled ray flowers. In botanical language they are called the Asteraceae. Previously, and still acceptably, they were termed Compositae.

In evolutionary time the daisy principle has ramified into a great many common plants. I've come across a considerable number of species within 33 genera of Asteraceae at Halibut Point, including sunflowers, thistles, wild lettuce, and dandelions.

Aster and Grass-leaf goldenrod (Euthamia graminifolia)

You may be surprised on careful examination to notice that goldenrod flowers are built on the daisy structure. That fact places them within the Asteraceae. They are close cousins of the aster. We saw in the last posting that our local goldenrods are split among two different genera, Solidago and Euthamia.

The captions on the pictures above hint at recent complexities in classifying our familiar asters. The over-arching genus Aster no longer applies to American species. The designation 'true asters' is reserved for certain relatives with evolutionary precedence from the Old World. Anyone who wants to stay up to date with botanical conversations will have to learn how to remember and pronounce some daunting terms for our latecomers.

In the next posting we will go afield at Halibut Point to consider eleven species growing there.