rachilla


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rachilla

[rə′kil·ə]
(botany)
The axis of a grass spikelet.
References in periodicals archive ?
A look into Figures 1, 2, 3 and 4 outlines a representation of the vascular system of a rachilla in the middle segment of the ear.
The anatomical studies of vascular bundles of rachilla (spikelet) in two other segments of spike (proximal and distal) showed that the pattern of vascularization in different florets was similar to that of central spikelets (Figure 3A, B and C).
As mentioned earlier, the first three grains namely F1, F2 and F3 were supported by the principal vascular bundles of the rachilla, though with varying magnitude, while the vascular system of the distal grains on each spikelets (F4 or F5) were sustained by sub-vascular bundles, a sub-division of the principal vascular cylinder after traversing a long distance.
The variety is a six-rowed, roughawned, long rachilla hair, white pearl spring barley.
The rachilla apex together with the distal glume (G1) is situated in between the lifted flower primordium (F2), and the developing flower (F3).
The flower is subtended by the spikelet prophyll, which forms an utriculus that envelops flower, rachilla and distal glume (Fig.
This spikelet prophyll or proximal glume is always positioned between the rachilla and the relative main axis (Kukkonen, 1994); it is often two-keeled, and always empty (except for the Dulichieae and Cariceae).
We suggest that while the hooks may be analogous, the bend in the rachilla where the hooks begin could provide a homologue for Uncinia s.
In Carex, rachilla proliferation often produces androgynous lateral spikes in teratological specimens (Snell, 1936; Smith & Faulkner, 1976), and presumably these spikes could become genetically fixed if there was a selective advantage.
3, for a similar result concerning the occurrence of a single floret and absence of rachilla extension around the nexus between Pooideae and Arundinoideae).
Although the most parsimonious interpretation of the character variation pattern detected in this study is that a single-flowered spikelet is plesiomorphic for the family, the later de novo development of a rachilla extension and subsequent additional fertile florets also is problematic.
1995) are consistent with the interpretation that a spikelet with one fertile floret (rarely with one or more sterile "lemmas" below the fertile one as in Ehrhartoideae), and lacking a developed rachilla extension above the fertile floret, was present in most early grass lineages and that this is the plesiomorphic form of the spikelet in Pooideae and the PACC clade.