The Verbena genus, commonly known as vervain, is a popular group of flowering plants appreciated for its long blooming season and clustered flowers. These plants, which can be annuals or perennials, thrive in full sun and attract pollinators. Understanding the appearance of their seeds is the first step for successful cultivation.
Physical Characteristics of Verbena Seeds
Verbena seeds are minute, making them challenging to handle during sowing. While size varies slightly by species, they are consistently small; for example, a single ounce of Verbena bonariensis seeds can contain approximately 122,000 seeds. Their shape is typically oblong or tear-drop, often featuring a slight curvature along the length.
Mature verbena seeds are usually dark, ranging from black to a deep grayish-brown, which helps them blend into the soil. The seed coat texture is not smooth but often features distinct ridges, grooves, or a rough, wrinkled surface. These microscopic surface details are characteristic of the plant family Verbenaceae and help distinguish them from other small seeds.
Where Seeds Develop and How to Harvest Them
Verbena flowers produce seeds within small, dried fruit structures called nutlets, which form after the blooms fade. These nutlets are contained within the dried calyx or flower head at the tip of the stem. Initially, the seeds and the surrounding pod are green, indicating they are not yet mature enough for collection.
The correct time to harvest is when the entire flower head and a significant portion of the stem have turned brown and dried out. Waiting too long may result in the seeds naturally dispersing, as the dry casings are prone to bursting open. The easiest collection method is to snip off the dried flower head, allow it to dry further if needed, and then gently shake or crush the head to release the ripe seeds.
Variations Among Popular Verbena Types
While the general description of a small, dark, ridged seed holds true for the genus, subtle differences exist between species. For instance, the seeds of the tall Verbena bonariensis (Purpletop Vervain) maintain the characteristic oblong shape but may be marginally larger or smaller than those of a compact annual variety, such as Verbena x hybrida.
The specific shade of the seed can also vary, with some species appearing nearly jet black and others presenting a charcoal or dark brown hue. These variations are minor but noticeable when comparing seeds from trailing hybrid bedding plants to those of more rigid, perennial types. Despite these distinctions, the overarching features of minute size and dark, textured appearance remain the defining look of verbena seeds.