also: ふるいかん
noun
sieve tube
Botanical term for the conducting element in phloem tissue of vascular plants.
師管は植物の師部にある通道組織です。
Sieve tubes are conducting tissues found in the phloem of plants.
From 師 (sieve) + 管 (tube). The kanji 師 is used here for its meaning 'sieve', though this usage is specialized.