The leaves of marigolds vary between species, exhibiting either opposite or alternate arrangements. They are predominantly pinnate, occasionally simple, and feature toothed margins dotted with glands. The leaves typically measure between 2 to 6 inches (5 to 15 cm) in length. Pinnate leaves display a central vein with lateral leaflets, while simple leaves are singular. The leaf color is a vibrant green, and when crushed, the glandular oil releases a distinctive aromatic scent.

The flowers of marigolds are typically solitary heads in vibrant shades of yellow or orange, measuring 0.5 to 4 inches (1.3 to 10 cm) in diameter. Some cultivars feature striking bicolor patterns. Depending on the species, the flowers can be solitary or grouped in dense corymbs, terminal, and heterogamous. The phyllaries are usually arranged in a single row, occasionally in two rows, with connate margins and glandular textures. These flowers are notable for their distinctive and elaborate structure.

The stem of marigolds is erect, measuring up to 3 feet (90 cm) in height. It has a smooth texture and exhibits a vibrant green color. The stem is moderately thick, with an average diameter of 0.2 inches (0.5 cm). Distal branches are notable, forming a well-branched structure towards the upper parts of the stem. The branching pattern is consistent, providing a balanced growth structure. No prominent nodes or unique markings are observed along the stem.

The fruit of marigolds is a type of achene, displaying a strikingly narrow, cylindrical shape. These fruits are notably pigmented with a deep black coloration that can serve as a distinct identifying marker. The texture is typically dry and hard, characteristic of achenes. A unique feature includes its pappus arrangement: a combination of one to three elongated setae and several shorter scales, ranging from seven to nine in number, which are adorned with ciliate margins. These scales are distinctively less in length than the setae, but play a role in the dispersal of the fruit.