Lamiids (Euasterids I)

Classification of Asterids

Food, Plant source foods, Flowering plats (angiospermae), Mesangiosperms, Eudicots, Core eudicots, Superastierds, Asterids

Consumption area(s): Earth

Note: For better understanding, please read the article on flowering plants (angiospermae) first. If you come across unfamiliar words, you can click on any highlighted term to open the glossary with definitions of key botanical terms.

Introduction

The group known as Lamiids, also called Euasterids I, includes a wide range of dicot seed plants that are part of the larger family of Angiosperms. These species are united by a set of common traits and genetic links, suggesting they stem from a shared origin.

This cluster forms one of the two main sections of the broader Asterid group, which brings together plants with similar structural and biological features. Through the study of their evolutionary patterns, researchers can trace how these plants have gradually branched out and adapted to different environments.

Description of Lamiids

Species within this group display a remarkable diversity of forms. Some grow as annual or perennial herbs, others develop into shrubs, and a number reach the stature of large trees, exceeding 20 meters in height but certain plants have adapted to aquatic environments. Some species, especially in the Boraginales and Gentianales, are coated with rough hairs.

The leaves are usually found in opposite pairs along the stem, though in some plants they may be alternate or arranged in a spiral. Stipules may be present or absent. In some species, they appear in whorls, either in pairs, groups of four, or in dense rings of up to seven leaves. Leaf bases can be sessile, petiolated, or may wrap partly around the stem (amplexicaul). Leaf shapes vary widely, from lanceolate to ovate, with margins that may be entire, lobed, toothed, crenate, or wavy. Pinnate leaves can also be found.

Their inflorescence may follow a cymose (determinate) or racemose (indeterminate) pattern. In certain families such as Lamiaceae, the flowers are arranged in stacked whorls along the stem, each whorl containing 2 to 20 flowers arranged in a circle, usually supported by two large bracts slightly separated from the main cluster. In other groups, the flowers may be arranged into spikes, forming a dense, elongated structure.

The flowers themselves are typically bisexual and tetramerous (composed of four whorl—calyx, corolla, androecium, and gynoecium). Most have a five-part structure, though some may feature just four elements per whorl. The sepals and petals are commonly fused, and in many cases, the corolla tube develops only after the free lobes appear, a trait considered characteristic of Lamiids. The stamens are epipetalous and occur in a number equal to or fewer than the corolla lobes.

The calyx in this group is typically composed of of fused sepals (gamosepalous) and mostly radially symmetrical (actinomorphic). It’s generally divided into 3, 4, or 5 lobes. The corolla is also fused (gamopetalous), most often displaying bilateral symmetry (zygomorphic). It usually forms a tubular shape, sometimes widening toward the tip, and ends in five lobes grouped into two main lips. A typical arrangement is 2 upper lobes and 3 lower, but other patterns are possible.

The androecium includes typically 2, 4, or 5 stamens, though numbers like 3, 6, or up to 8 can also be found. Often, one or more stamens are sterile, reduced to small, non-functional staminodes. When four stamens are present, they are often didynamous—two longer and two shorter. The filaments are attached to the corolla, with the upper part remaining free, and can be either hairy or smooth.

The anthers may be closely paired, either glabrous or pubescent, and usually with bilocular structure. Most often, they open along their length (longitudinal dehiscence), though some use valves. Most pollen is tricolpate, though other forms with varied apertures exist. A nectary disk, often with lobes, is well developed and typically produces abundant nectar.

The gynoecium features a superior ovary and is formed by two (rarely three) fused carpels. This results in an ovary with 2 to 4 chambers, shaped by false septa. The placentation is axile, and ovules, numbering between 2 and 10, or even up to 100, have a single integument and are tenuinucellate, meaning the nucellus is reduced to a few cells. The endosperm forms via the cellular type of development. The style, arising from the base of the ovary (gynobasic), is typically slender. The stigma is usually bifid, with equal or slightly unequal lobes. The syncarpous ovary, where the carpels are fully united into one pistil, is a defining feature of this group.

The fruit varies greatly: it can be dry or fleshy capsules, drupes, or schizocarps, and comes in many shapes—rounded, lobed, oblong, or ellipsoid. Fruit opening mechanism also differ: some are explosive, others septicidal, or circumscissile. Some fruits remain indehiscent, with a woody or leathery texture. In Boraginales, the fruit commonly breaks into four nutlets, though occasionally only two develop.

Pollination in this clade is primarily carried out by a variety of insects, involving a variety of insects like bees, wasps, butterflies, moths, flies, and beetles, as well as birds in some cases. Some species produce cleistogamous flowers, which remain closed and self-pollinate. In groups such as the Bignoniaceae, large flowers are adapted for pollination by large animals, and the vast diversity in flower shapes often reflects differences in pollinator behavior. Brightly colored corollas and showy bracts further enhance pollinator attraction.

Reproduction is achieved through standard pollination mechanisms. Seed dispersal varies: many seeds fall to the ground after being carried a short distance by the wind, but their further spread often depends on ants. These seeds typically bear elaiosomes, oil-rich appendages that attract ants looking for food. In species with drupe, birds and mammals are the main agents of dispersal. Other plants rely on water to spread their seeds.

Classification of Lamiids

This clade is divided into the following orders:

• Boraginales (anchusa, borage)
• Gentianales (coffee, gentian, mangosteen)
• Icacinales (african icacina or false shea)
• Lamiales (basil, mint, rosemary, sage, thyme)
• Solanales (bell peppers, chili peppers, potatoes, tomatoes)