Dichasium

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Related to dichasia: dichasium, Racemes

dichasium

[dī′kā·zhē·əm]
(botany)
A cyme producing two main axes from the primary axis or shoot.

Dichasium

 

the inflorescence in plants of the cymose type. The primary axis in dichasium ends in a single apical flower. From the two opposite axils under that flower two lateral branches develop that exceed the primary axis in height and also end in flowers, which blossom later. On each of them in turn, two more lateral branches develop that overtake them in height and end in apical flowers, which blossom still later, and the process continues. Dichasium is typical for many plants of the family Caryophyllaceae and others. Sometimes branching and growth in dichasium is disturbed somewhat and inflorescences form that outwardly do not resemble dichasium (as in so-called false whorls in plants of the family Labiatae).

References in periodicals archive ?
However, these two species differ in a number of important diagnostic traits, mainly regarding the order of branching and the position of the dichasia (see above).
Species similar to Psittacanthus lasianthus, from which it differs by the sympodial, densely puberulous, three-angled stems, ternate leaves, terminal dichasia, perfoliate bracts, a neck-bearing, not inflated corolla densely laciniate on its outer surface and a triangular, ligule on the inside of each petal, a ring-like nectary, and a micropapillose stigma versus percurrent, glabrous, circular stems, paired leaves, axillary dichasia, not perfoliate bracts, a neck-lacking, inflated corolla without laciniae on its outer surface and a finger-like ligule on the inside of each petal, a 4-lobed nectary, and a smooth stigma in P.
It should be noted that, in some genera, the flowery shoots have an inflorescence that has been described (Townsend, 1993) as solitary or clustered axillary spikes (Nothosaerva Wight); solitary or fasciculate (Alternanthera); with very small hermaphrodite flowers, in few axillary flowered sessile clusters or in dichasia (Tidestromia Standley, Sanchez-del Pino & Flores Olivera, 2006); with hermaphrodite flowers, either solitary or paired in the axils of upper leaves (Polyrhabda).
Solitary flowers, Stebbins (1973, 1974) pointed out, are usually derived in primitive families; as an example, the solitary flower of Zygogynum is the exception in Winteraceae, in which all other taxa have axillary cymes or dichasia.
Inflorescence mostly cymose (usually a small dichasia or a much branched cymose panicle), rarely solitary or sessile (Theligonum).