Japanese pepper tree
椒 refers specifically to the Japanese pepper tree, a plant whose berries are used as a spice.
椒 combines 木 (tree) with 叔, which likely contributes the sound. The character originally referred to a type of pepper tree.
The left side 木 is a tree, and the right side 叔 looks like a hand picking small fruits. Imagine a tree whose small berries are harvested for pepper.
For ショウ, picture a pepper tree growing in a show garden: show -> ショウ, and the tree's spicy berries are the star of the display.
pepper
Japanese pepper (species of Sichuan pepper, Zanthoxylum piperitum); Japanese prickly ash
Japanese giant salamander (Andrias japonicus)
salamander
Chinese-style stir-fry containing green peppers and meat; pepper steak (US)
sweetened mochi flavoured with Japanese pepper
green Japanese peppercorn; unripe Japanese peppercorn
pieces of young pepper tree branch (used medicinally or for pickling)
size isn't everything; something might be small but still pack a punch; Japanese pepper is small-grained but has a tongue-numbing tingle
ashy minivet (species of passerine bird, Pericrocotus divaricatus)
floating watermoss (Salvinia natans)
mochi with sanshō (Sichuan pepper)
buchi salamander (Hynobius naevius)
condiment paste made from yuzu zest and chili peppers (chile)
ailanthus-like prickly ash (Zanthoxylum ailanthoides)
mastic-leaf prickly ash (Zanthoxylum schinifolium); Japanese prickly ash; Japanese pepper
Japanese clawed salamander (Onychodactylus japonicus)
garden cress (Lepidium sativum)
crescent sweetlips (species of fish, Plectorhinchus cinctus)
Chinese prickly-ash (Zanthoxylum bungeanum); Sichuan pepper (spice); Szechuan peppercorn