Summary of the types of photosynthesis in Poaceae

and corresponding leaf anatomy

C3 PHOTOSYNTHESIS occurs in all all Bambusoideae, Oryzoideae, Pooideae and most Arundinoideae. Grasses with this type predominant in shady, cool, and/or moist sites. The corresponding leaf anatomy includes mesophyll that is usually loosely packed, irregularly arranged, and uncompartmentalized. The parenchyma and mestome sheath are usually without chloroplasts, or at least with much less compared to adjacent mesophyll cells. Carbon fixation and the C3 cycle occur in the mesophyll cells.

  1. Bambusoideae and Oryzoideae (p. 41 - note arm and fusoid cells).
  2. Pooideae (p. 40).
  3. Arundinoideae (p. 42). Note the dense and radiate mesophyll, reminiscent of C4 grass anatomy.

C4PS - ASPARTATE PHOTOSYNTHESIS (p. 46). This type occurs in all Chloridoideae, and a few Arundinoideae and Panicoideae. Grasses with this type predominant in arid, sunny, and/or warm sites. The corresponding leaf anatomy includes mesophyll that is radiated and densely packed, an enlarged parenchyma sheath with chlorophyll, and a smaller mestome sheath without chlorophyll. Each vascular bundle and closely associated mesophyll is compartmentalized. Carbon fixation occurs in the mesophyll, and the C3 cycle occurs in the parenchyma sheath.

C4dPS - MALATE PHOTOSYNTHESIS (p. 45). This type occurs in all Aristideae. Grasses with this type predominate in arid, sunny, and/or warm sites. The corresponding leaf anatomy includes mesophyll that is radiated and densely packed, 2 parenchyma sheaths with chloroplasts, and no mestome sheath. Carbon fixation occurs in the mesophyll and the C3 cycle occurs in the innermost parenchyma sheath.

C4MS - MALATE PHOTOSYNTHESIS (p. 43, 44). This type occurs in nearly all Panicoideae. Grasses with this type predominant in humid, sunny, and/or warm sites. The corresponding leaf anatomy includes mesophyll that is usually irregular and loosely packed, no parenchyma sheath, and an enlarged mestome sheath packed with chloroplasts. Vascular bundles are not compartmentalized, and a close association with the mesophyll cells is attained by proliferation of secondary vascular branches throughout the mesophyll. Carbon fixation occurs in the mesophyll and the C3 cycle occurs in the mestome sheath.

Back to presentation of Bambusoideae and Oryzoideae.