Goldenrod

Solidago

Description:

Solidago species are perennials growing from woody caudices or rhizomes. They have stems that can be decumbent to ascending or erect, ranging in height from 5 to 100 or more centimeters. Some species have stems that branch near the top. Some Solidago species are hairless others have strigose, strigillose, hispid, or short-villous hairs. The basal leaves in some species remain persistent through flowering, while in others the basal leaves are shed before flowering. The leaf margins are often serrate, and leaf faces may be hairless or densely hairy; the distal leaves are sometimes 3-nerved, and hairless or sparsely to densely hairy with scabrous, strigillose, or villous hairs. In some species the upper leaves are stipitate-glandular or sometimes resinous. The flowering heads usually radiate, sometimes discoid, with (1–)2 to 1500+ florets in racemiform (club-shaped or pyramidal), paniculiform or corymbo-paniculiform, or sometimes secund arrays. The involucres are campanulate to cylindric or attenuate. The ray florets are pistillate and fertile. The corollas are yellow or rarely white and are usually hairless. The disc florets are bisexual and fertile and number 2 to 35 typically, but is some species there maybe up to 60 florets. The corollas of the disc florets are yellow and the tubes are shorter than the throats. The fruits are cypselae, which are narrowly obconic to cylindric in shape, they are sometimes somewhat compressed. The cypselae have 8 to 10 ribs usually and are hairless or moderately covered with stiff slender bristles. The pappi are persistent with barbellate bristles.[1] The many goldenrod species can be difficult to distinguish, due to their similar bright, golden yellow flower heads that bloom in late summer. Goldenrod is often unfairly blamed for causing hay fever in humans. The pollen causing these allergy problems is mainly produced by Ragweed (Ambrosia sp.), blooming at the same time as the goldenrod, but is wind-pollinated. Goldenrod pollen is too heavy and sticky to be blown far from the flowers, and is thus mainly pollinated by insects.Frequent handling of goldenrod and other flowers, however, can cause allergic reactions, leading some florists to change occupation. Solidago species are easily recognized by their golden inflorescence with hundreds of small capitula, some species have their flowers in spike-like inflorescences and others have axillary racemes. They have slender stems, usually hairless but S. canadensis shows hairs on the upper stem. They can grow to a length between 60 cm and 1.5 m. Their alternate leaves are linear to lanceolate. Their margins are usually finely to sharply serrated. Propagation is by wind-disseminated seeds or by spreading underground rhizomes which can form colonies of vegetative clones of a single plant. Goldenrod and visiting Cerceris wasp They are mostly short-day plants and bloom in late summer and early fall. Some species produce abundant nectar when moisture is plentiful, or when it is warm and sunny.