Spindle trees leaves are variable in size, ranging from 1/2 to 6 inches (1.3 to 15 cm) long. They are arranged alternately, subopposite, or opposite and may cluster on short shoots. The leaves are simple with small stipules, featuring either entire or toothed margins. The venation is pinnate, giving them a structured appearance. Leaf color can vary, but they are generally green, with a smooth or slightly textured surface, making them a key identification feature.

Spindle trees features small, 4-parted flowers that can be white, red, yellow, green, or purple. Each flower, typically greenish maroon, consists of three to six persistent sepals, which can be either free or united at the base. The plant’s flowers appear in terminal or axillary cymes, often accompanied by a present disk. They have two to six stamens with filaments partly united, measuring around 0.2-0.3 inches (5-8 mm) in diameter, and bloom in late spring to early summer.

The stem of spindle trees is characterized by being terete, meaning it is cylindrical in shape, but can also be 4-angled. This unique structure is smooth to the touch and may show ridges along the angles. The color of the stem typically ranges from green to a light brown as it matures. Stems are moderately thick, about 0.25 to 0.5 inches (0.6 to 1.3 cm) in diameter, and exhibit a branching pattern that is often opposite or whorled, making identification distinct.

The fruit of spindle trees is a striking capsule with a fleshy, variably-colored exterior ranging from reddish, pink, ivory to yellow. Upon maturity, the capsule distinctively splits open, revealing its vivid orange-red seeds, which are nestled inside. The overall form of this fruit can present as a capsule, a berry, or occasionally as a drupe; some species may exhibit winglike features. Typically, it catches the eye with its bright seed display, a key characteristic for recognition. The descriptors provided signify the fruit's visual allure and assist in its identification.