By September, virtually all of the native plants in the Puget Lowlands that spread by seed have gone to seed. In this blog I take a closer look at eight of them arranged by their means of seed dispersal. In recent weeks I took some pictures in the field and under a microscope at home.
Wind-Dispersed Seeds
The wind-dispersed seeds of several of our native plants have pappuses that carry them far and wide on currents of air.
Douglas Aster — Symphyotrichum Subspicatum
Seedhead of a Douglas Aster — Though I am not a botanist, I believe that the dark filaments amidst the pappuses may be from ray flowers.Seeds of Douglas Aster Under the Microscope — I believe these may be seeds from ray flowers.A Single Douglas Aster Seed Under the Microscope. I believe this may be the seed from a disc flower.
Willowherb – Genus Epilobium, Species Probably Ciliatum
On this Willowherb seedhead, two pods are still ripening, and one has already dried and split with its seeds mostly dispersed.A closer look at a fully ripe Willowherb seedhead with most of its seeds dispersed. I’m still trying to get a good picture of the seeds when the pod first opens, and the seeds are perfectly lined up.Willowherb Seeds Under the Microscope
Animal-Dispersed Seeds
Several of our native plants have seeds with hooks or bristles that stick to fur and clothing.
By September most of the Large-Leaved Avens have produced their brownish seedheads atop long, thin stems.Zooming in, the tiny hooks on the end of each seed become visible.A Large-Leaved Avens Seedhead Viewed Under the MicroscopeThe individual seeds at the top of this seedhead are beginning to disperse.According to Pojar/MacKinnon, the Nuxalt called these seeds “lice.” The tiny hairs may add to their stickiness.
Sweet Cicely — Osmorhiza Berteroi
The seeds of Sweet Cicely average about ¾” long.Viewed under a microscope, it appears that tiny, stiff bristles are what makes Sweet Cicely seeds stick to fur and clothing (e.g., the backs of cloth gloves).
Cleavers – Galium Aparine
Cleavers — Gone to Seed and Draped Over Shrubs — Like the Sweet Cicely, the sticky seeds of Cleavers can be annoying when hand weeding.The seeds of Cleavers form at the end of thin stems.Even viewed under the microscope, the tiny, hooked spikes on the surface of the Cleavers’ seeds are barely visible. Despite their small size, they are incredibly adept at clinging to cloth and fur.
Gravity-Dispersed Seeds
It’s not clear how some tiny seeds are dispersed much further than a few feet from their parents.
Penstemon – Genus Penstemon, Species Probably Serralutus
Penstemon Seed Pods at the Top of a StalkA Penstemon seed pod under the microscope begins to spill its tiny, irregularly-shaped seeds.
Yarrow – Achillea Millefolium
Yarrow SeedheadsVery Tiny Seeds of Yarrow Under the Microscope
Hedge Nettle – Genus Stachys, Species Probably Mexicana
