Onion family (Alliaceae)
The onion family (about 750 species in the textbook) grows almost everywhere except Australia; modern systems treat it as the subfamily Allioideae of Amaryllidaceae. They are bulbous perennial herbs. The bulb is a shortened underground shoot whose fleshy scales are leaf bases. Leaves are swollen, flat or thread-like, stalkless, with a tube-like base. The inflorescence is a simple umbel wrapped in a thin sheath until it opens. Flowers are bisexual, regular; the perianth is simple with 6 tepals (two whorls), 6 stamens, one pistil (of 3 carpels); the fruit is a capsule. Formula: P3+3 A3+3 G(3). The common onion (Allium cepa): flower stalk up to 100 cm, swollen in the middle and hollow, a ball-shaped umbel, whitish-green flowers in May–June, fruit ripe in July. Onion and garlic (Allium sativum) are rich in phytoncides: these substances kill microbes or stop them multiplying. Among wild species the mador (matur) onion and anzur onion are eaten, while flower onion and others are ornamental; 10 species are in the Red Book. Cutting an onion releases volatile substances that sting the eyes.
Experiment: grow an onion bulb and a garlic bulb half-immersed in water in two containers; every 3 days measure root and leaf length and record it in a table. Safety: only adults use the knife; rinse onion juice from the eyes with clean water; do not eat rotten bulbs; wash hands.