I came across hieroglyphic writing 𓇗¹ for sedge² while I had just learned the kanji for the same word in Japanese.
The reference is here.
It says that in hieroglyphic writing, the sign for the sedge plant functions as a triliteral (three consonants), used to write king.
Japanese spelling is with the originally Chinese glyph 菅.³
The actual Japanese word is suge /sɯge/. I guess the more friendly spelling is kana spelling すげ or スゲ but I’m looking at the kanji spelling now.
The word suge is unrelated to the Chinese word 菅. That word might have been, in transcription, something like kaen (for its original meaning, see below).
In Classical Chinese the bottom element 官 in the glyph 菅 gave a hint at the pronunciation of the word (sounds something like kwan) while the top part 艹 (the semantic element or determinative) told the reader: the word is some kind of plant (艹 is an abbreviation of grass 艸)
How did a Chinese reader in the Middle Ages know that 官 gave the hint kwan? Because 官 was a word that one was supposed to know.
官 itself does not contain a hint for its pronunciation. It does contain a determinative (宀, indicating a building) but the element below that is ambiguous. Today, the bottom part of 官 is often taken as buttocks because the modern meaning of the word 官 is government official and those officials are supposed to sit on their buttocks in a building.
In practice 官 is like 4 in English. Just like you just have to learn that 4 stands for the word four, you also just have to know that 官 stands for guān (in modern Chinese).
Speculatively, a really really smart Chinese reader may be able to guess that 官 might have some semantic relation to the Classical Chinese meaning of 管 (a hollow tube, pipe, a flute, modern Chinese pronunciation guǎn) and make a connection to the shape of sedge. But probably unlikely, since the graph 管 came to be used⁴ for a word administer.⁵
In Japanese, 菅 is even more arbitrary as a writing symbol than it is in Chinese, because the phonetic hint kwan is useless for the Japanese word suge. In this respect, 菅 is almost comparable to the Hindu–Arabic numeral symbol 4, which is also used in Japan today to write the number word yón.
And yet, 菅 is not quite the same as 4. It contains the upper component 艹, which functions as a determinative for plant-related words. And even in Japanese, there may be a small (very small? negligible?) chance that readers associate 菅 with 管.⁶
In hieroglyphic, the sign for sedge gives the reader the three consonants of the word king (see this example).
The readers of Classical Egyptian had of course to supply the vowels themselves, but that seems to have been a minor thing if Classical Egyptian was your mother tongue.
However, just as with Chinese characters, to avoid ambiguity, Egyptians might add a determinative to their symbols. In the case of the word king, a determinative indicating a king. In the case of the word plant, a determinative indicating a plant.⁷
The Classical Chinese word 菅 was has this description in MOEDict:
菅 jiān [also guān]
Noun
A plant name. A perennial herb of the grass family (Poaceae, 禾本科), genus Jiān (菅屬). Stems and leaves grow in dense clumps from a persistent rootstock. The leaves are slender, long, and pointed, often with fine hairs. From the upper leaf axils of the stem arise racemose inflorescences arranged in a panicle. The roots are short and tough, and can be used to make brooms.Verb
Figurative: to treat lightly or with contempt; to regard as insignificant. Example: 草菅人命 — “to treat human life as worthless.”
A guess at equivalents in English would be: sedge, reed grass, coarse grass, thatch grass, broom grass, wild grass.
