Woodland Sunflower – Helianthus divaricatus

helianthus divaricatus disc flower_00This photograph, with the Woodland Sunflowers growing at the edge of woods, certainly illustrates their name.  They are growing on a rather high bluff, 1/2 mile high and about 1/2 a mile away, as the crow flies, from the Nantahala River.  The Helianthus divaricatus was featured in a previous post, “Four Nantahala sunflowers and bugs who love them”. These plants do, indeed grow along river, on the mountain side, as they prefer ground that is dry.

They are tall plants, between 2-7 feet tall, and because the do prefer dry woods and open spaces where they get a lot of sun and thus dry ground, they stand erect,  which the sunflowers preferring moister ground don’t,  and tend to bend over.  They spread by sending out long rhizomes.  Rhizomes are not simply roots – they have buds and nodes on them which sprout up and make other plants, so the Woodland Sunflowers tend to present in colonies as one plant will send out a rhizome which will make into a plant very near by the first one, and so on.

helianthus divaricatus disc flower_05Since becoming interested in wildflowers and native plants in general, I have begun to change my perception of them due to language I encountered in books  as I was trying to thumb through them finding pictures matching my discoveries which described the plants in botanical terms.

Sunflowers are just that FLOWERS.  Plural.  Although we say “A sunflower” what we should be saying is “Sunflowers”, plural.   When there is more than one flower on a stem, it is called inflorescence. Actually, even if it is only one “inflorescence” on the stem, botanists, I have discovered, refer to what we would normally call “a flower”, as an inflorescence.

The sunflowers have two types of flowers, DISK flowers, and RAY flowers.  The photograph above illustrates this multiplicity of flowers which compose a sunflower.  The disk flowers are those tiny little flowers which the camera can capture so well and is really too small for us to notice that it is composed of many little flowers.  The ray flowers are the yellow petals that surround the disk.  Of course, those little tiny flowers have nectar in them and are just the right size for insects to enjoy.

helianthus divaricatus and tiger swallowtail_5

helianthus divarictus - 2008_09

The leaves of the Woodland Sunflower are opposite and “sessile” which means that they don’t have a stalk attaching the leaf to the stem ( a petiole) but are directly attached to it, as illustrated in photograph below.

helianthus divaricatus leaves_2

At the base of an inflorescence the are small leaves, or bracts,  which forms the involucreSometimes being familiar with terms which describe a flower or inflorescence is critical because one needs to understand what botanists are referring to in order to make proper identification.

For example, a few hundred feet from the particular colony of Woodland Sunflowers is another colony of sunflowers but the leaves are not sessile (without a stalk) but do have a little stalk  (petiole) and the leaves are sharply toothed.  Although at first glance, or even on close examination,  the plant seems to be the same one because they are the same size and shape and have very similar flowers, by noticing details of the plant one begins to see that although similar and related, it is not the same plant.

Noticing the involucre of the Woodland Sunflower is not that critical, but does it make an interesting photograph!  helianthus divaricatus_2 - Copy

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