Table 3.

Primary and secondary metabolites identified by histochemical and fluorescence tests in the trichomes of Orobanche picridis flowers

Metabolites	Test	Calyx			Corolla			Stamens	Colour observed
		Capitate glandular trichomes			Capitate glandular trichomes			Non-glandular trichomes
		Head cells	Neck cells	Stalk cells	Head cells	Neck cells	Stalk cells
Polyphenols	FeCl3 Toluidine Blue O	++ ++	+ ++	+ +	++ ++	+ ++	+ +	+ –	Dark brown Blue, violet, turquoise
Tannins Total lipids	Potassium dichromate	++	+	+	++	+	+	+	Brown
	Sudan Red B and Sudan IV	+	+	+	+	+	+	+	Orange
Acidic and neutral lipids (essentials oil)	Nile Blue	+	+	+	+	+	+	+	Blue, pink
Essential oil	Nadi reagent	–	–	–	–	–	–	–	Dark blue, dark violet
Sesquiterpenes	Conc. H2SO4	+	+	–	+	+	–	–	Yellow
Lipids (essential oil)	Neutral Red under UV	+	++	–	+	++	–	–	Yellow
Terpenes contains steroids	Antimone trichloride under UV	–	+	–	–	+	–	–	Yellow
Lipids (essential oil)	UV-autofluorescence	+	+	–	+	+	–	+	Yellow
Acidic polysaccharides	Ruthenium Red	+	–	–	+	–	–	–	Red
Neutral polysaccharides	Periodic acid-Schiff’s reagent	+	+	+	+	+	+	+	Pink
Alkaloids	Wagner reagent	++	+	+	++	+	+	–	Brown
Flavonoids	Aluminium chloride and magnesium acetate under UV	++	+	+	++	+	+	+	Yellow

++ intensive, + positive, − negative