Triticum aestivum L. subsp. aestivum (common wheat)

Triticum aestivum subsp. aestivum caryopses generally have a plump rounded cheek area on either side of the crease which Triticum turgidum subsp. durum often lack. Also, the pinched rim or ridge around the durum wheat embryo is absent in common wheat. The brush of hairs opposite the embryo end are often thicker and more obvious in common wheat. Cross sections of the common wheat caryopsis reveal a white endosperm that may be hard or very mealy, whereas durum wheat is generally yellow in colour and hard (although it can also be white and soft).

×Triticosecale spp. Wittm. ex A. Camus (triticale)

×Triticosecale spp. caryopses have a surface texture generally with more obvious transverse wrinkles than those of T. turgidum subsp. durum. Another feature of ×Triticosecale is that the outer layer of the caryopsis is often flaky and loosely adhered to the internal portion, which is not seen in durum wheat. The embryo of ×Triticosecale spp. generally lacks the pinched ridge around the embryo as in durum wheat and the endosperm is white and not the usual yellow colour of durum. The brush of hairs appears more obvious in ×Triticosecale spp. than durum wheat’s, which may appear to be missing or is comprised of short hairs.

Triticum turgidum L. subsp. dicoccon (Schrank) Thell. (Triticum turgidum Dicoccum Group) (emmer).

T. turgidum subsp. dicoccon is not a free-threshing species and is generally in spikelet form (Wieser et al. 2020). Emmer caryopses are generally long oval shaped with both ends relatively narrow in comparison to durum wheat. The embryo extends further past the margin of the caryopsis in emmer than it does in durum wheat and the end opposite the embryo has a brush of long hairs. The brush of hairs is much more obvious than durum wheats.

Triticum turgidum L. subsp. turanicum (Jakubz.) Á. Löve & D. Löve (kamut; khorasan wheat)

Some authors refer to kamut as Triticum turgidum subsp. durum (FNA 1993+; USDA-ARS 2024), whereas other literature places it as a separate subspecies of Triticum turgidum known as turanicum (Feldman and Levy 2023). Khorasan wheat is often referred to as kamut, which is a common cultivar name (Feldman and Levy 2023). T. turgidum subsp. turanicum caryopses are longer than durum wheat with long straight sides giving it an oblong shape. The profile of kamut’s caryopsis is less humped than durum wheats. The grooved side of the caryopsis often has a slight arch so that when placed lying on this side, a hollow area can be seen.

Triticum monococcum L. subsp. monococcum (einkorn)

T. monococcum subsp. monococcum, like spelt and emmer, is considered a hulled wheat (Longin et al. 2016). T. monococcum subsp. monococcum caryopses are strongly laterally compressed so that the embryos are located on the narrow edges. The embryo of T. monococcum subsp. monococcum noticeably extends further past the margin of the caryopsis than it does in T. turgidum subsp. durum.