Tall purple flowers are not the product of a single species but belong to dozens of different plants across various botanical families, such as the mint family (Lamiaceae) and the aster family (Asteraceae). Identifying the specific plant hinges primarily on its location: whether it was seen in a managed garden environment or growing wild in a naturalized setting. Narrowing down the possibilities requires looking closely at the structure of the plant and its flowering habit.
Most Common Cultivated Examples
The most dramatic tall purple flowers seen in cultivated settings are often used for strong vertical accents. The genus Delphinium, commonly known as Larkspur, represents some of the tallest examples, with some hybrid varieties reaching heights of six to eight feet. These plants produce dense, towering spires of flowers that can be true blue, violet, or deep purple, typically blooming in the early to mid-summer months.
Liatris, often called Blazing Star or Gayfeather, offers a unique textural element in the garden, growing to a mature height of two to five feet. The flowers form dense, bottlebrush-like spikes of fuzzy purple florets that bloom sequentially from the top of the stalk downward, an unusual characteristic among spike-flowering plants. This North American native is a magnet for butterflies and typically blooms from mid-summer into the early fall.
Tall varieties of Salvia (Sage) are cultivated for their long-lasting color and heat tolerance, with some species reaching five to six feet. These plants produce deep purple, tubular flowers clustered along upright spikes, often attracting hummingbirds and blooming continuously from late spring until the first frost.
Tall Purple Flowers Found in the Wild
When a tall purple flower is spotted in an unmanaged or naturalized area, the possibilities shift toward native or invasive species. Vernonia species, collectively known as Ironweed, are robust native perennials found across North America, particularly in moist meadows and along roadsides. These plants easily grow between five and eight feet tall and produce large, flat-topped clusters of deep purple flowers in the late summer and early fall.
Another plant found in wild, moist environments is Lythrum salicaria, or Purple Loosestrife, which is considered an invasive species across much of North America. This perennial develops woody, square stems that can reach heights of four to ten feet, topped with dense, magenta-purple flower spikes that bloom from July through September. Its ability to rapidly outcompete native wetland vegetation makes it an ecological concern, despite its attractive appearance.
Key Features for Identification
Accurate plant identification relies on observing specific structural details beyond flower color and height. The arrangement of the leaves along the stem is a fundamental clue, such as whether they emerge opposite each other, alternate position, or form a whorl of three or more leaves. The cross-section of the stem is also telling; for example, plants in the mint family, such as Salvia, possess a distinct square stem, while others like Delphinium have round, hollow stems.
The form of the flower cluster, or inflorescence, is another defining trait. A flower head composed of many tiny florets tightly grouped into a dome or flat cluster, known as a capitulum, is typical of the Aster family, which includes Ironweed. Conversely, flowers with bilateral symmetry, meaning they can only be divided into mirror-image halves in one plane, are characteristic of the snapdragon-like blooms of Aconitum (Monkshood). Observing whether the flowers are tightly packed on a singular spike or branched into a loose, airy spray provides further evidence for a positive identification.
Important Toxicity Warnings
Many tall purple flowers are highly toxic, and positive identification must be confirmed before any handling or interaction beyond simple observation. Delphinium, a common garden choice, contains toxic alkaloids that can cause severe digestive upset if ingested by people or pets. The entire plant is considered poisonous, presenting a risk to grazing animals.
A plant often mistaken for Delphinium is Aconitum napellus, or Monkshood, one of the most poisonous plants commonly grown in gardens. Monkshood contains the potent neurotoxin aconitine, which can be absorbed through the skin, causing initial symptoms like tingling and numbness. Ingestion is extremely dangerous, as aconitine directly affects the nervous system and the heart. For safety, never consume or handle any unknown plant without gloves, especially if children or pets are present. Always research a plant’s toxicity before introducing it to a home garden.