Boraginaceae: Borage Family — Popcornflowers
Most members of the Borage family have their flowers arranged in coiled (scorpiod) cymes. They bloom from the base upwards, gradually unfurling like a scorpion’s tail or caterpillar, as new flowers emerge.
Popcornflowers are extremely challenging to identify in the field. All of them have similar white flowers, varying only in size and in the appearance and color of the “appendages”. These are located at the base of the corolla lobes, and are sometimes yellow, sometimes white and occasionally absent. Do not rely too heavily on the appendage color, as this can often vary on the same plant, or even the same flower head. The growth habits, size and hairiness of the plants cover a wide range, so it’s hard to use these as for identification.
The key distinguishing characteristic is to be found in the nutlets. First, the distinction between Cryptantha and Plagiobothrys is that the inner surface of Cryptantha nutlets has a distinct longitudinal groove. Plagiobothrys nutlets lack this groove, but instead have a distinct attachment scar below the middle of the inner surface.
Second, especially within the Cryptantha, count the nutlets (between 1 and 4), decide whether they are rough or smooth, and then examine their individual shapes. The problem is that the nutlets are all small, sometimes very small, and it is hard to come to any conclusions without a microscope.
With Plagiobothrys, one can narrow the choices by seeing whether a plant has any opposite leaves. One of the most common, Rusty Popcornflower (P. nothofulvus) has another unusual characteristic — the calyx is circumscissile in fruit, meaning that the top separates from the base like a lid. Nutlets are generally 4 in number, variable in their shape and appearance.
Enjoy these pretty little flowers, but be warned that you will need a proper botanical key, a microscope, and a good deal of practice to identify individual species with confidence. This page illustrates a small number of species, more to show some of the variations than to act as a guide to identification. The fingernail is included in some of the photos for scale; it is exactly 1 cm across at its widest point.