Subfamilies Panicoideae and Chloridoideae
Definition
Two of the major grass subfamilies. Panicoideae (warm-season C4 grasses of humid tropics and subtropics) are characterised by bilobate and cross-shaped phytoliths. Chloridoideae (warm-season C4 grasses of semi-arid and arid regions) produce a high proportion of saddle-shaped phytoliths. These signals allow broad habitat characterisation from phytolith assemblages.
- Field
- Phytolith analysis, forensic botany
- Panicoideae habitat
- Warm-season C4, humid tropics and subtropics
- Panicoideae marker
- Bilobate and cross-shaped phytoliths
- Chloridoideae habitat
- Warm-season C4, semi-arid and arid regions
- Chloridoideae marker
- High proportion of saddle-shaped phytoliths
Common questions
How does a phytolith assemblage help place a crime scene or a suspect?+
A soil or trace sample carrying a high proportion of saddle-shaped phytoliths suggests contact with an arid-zone grass environment, while bilobate and cross-shaped forms point toward a humid tropical or subtropical setting. Comparing that signature against the geography a suspect claims to have visited can support or contradict their account.
Can a single phytolith shape reliably identify one of these subfamilies on its own?+
Not reliably. Analysts work from the overall proportion of shape types in an assemblage rather than any one phytolith, because individual shapes can occur at low frequency across more than one grass subfamily and local reference collections are needed to calibrate the interpretation.
Related terms
- Caryopsis
- The grain of a grass: a single-seeded fruit in which the seed coat is fused to the ovary wall. Shape, size, and...
- Floret
- The basic reproductive unit of a grass spikelet, consisting of the lemma, palea, and the enclosed flower. Floret morphology, including lemma surface,...
- Lemma
- The lower of the two bracts enclosing the grass floret. Its surface texture, venation, awn character, and marginal features are major identification...
- Morphotype
- A phytolith shape class defined by the geometry of the silica body: bilobate, cross-shaped, saddle-shaped, elongate, dendritic, and so on. Individual morphotypes...
- Phytolith
- Opaline silica body precipitated in or between plant cells during growth. Grass phytoliths are produced in high quantities and persist in soil...