Because the adjectives big and red modify this head noun, they are its dependents.
The conventions illustrated with these trees are just a couple of the various tools that grammarians employ to identify heads and dependents.
Henceforth the convention is employed where the words appear as the labels on the nodes.
Since some prominent phrase structure grammars (e.g. most work in Government and binding theory and the Minimalist Program) take all branching to be binary, these head-medial a-trees may be controversial.
Trees that are based on the X-bar schema also acknowledge head-initial, head-final, and head-medial phrases, although the depiction of heads is less direct.
The standard X-bar schema for English is as follows: This structure is both head-initial and head-final, which makes it head-medial in a sense.
Some language typologists classify language syntax according to a head directionality parameter in word order, that is, whether a phrase is head-initial (= right-branching) or head-final (= left-branching), assuming that it has a fixed word order at all.
English is more head-initial than head-final, as illustrated with the following dependency tree of the first sentence of Franz Kafka's The Metamorphosis: The tree shows the extent to which English is primarily a head-initial language.
Structure is descending as speech and processing move (visually in writing) from left to right.
This fact is obvious in this tree, since structure is strongly ascending as speech and processing move from left to right.
It is also common to classify language morphology according to whether a phrase is head-marking or dependent-marking.