The Apennine Indigo

Habit: A perennial herb 10-30 cm tall. Leaves: Lower leaves spatulate, about 4-5 cm long and 1 cm wide, crossed by a single central vein. Stem leaves crowded, with a hastate-clasping base, bearing two arrow-shaped basal lobes that directly clasp the stem. Flowers: Arranged in an inflorescence of small yellow flowers. Sepals ovate, about 3 mm long; petals spatulate and slightly longer, 4-5 mm. The flower structure is typical of the Brassicaceae, with four petals arranged in a cross. Fruits: A pendulous, elliptic silicle containing a single flattened seed surrounded by a wing that aids dispersal. Flowering: May-August.

Chorological type: Subendemic. Distribution: In Italy the species occurs along the Central Apennines and in the central and western Alps. Habitat: It grows exclusively on calcareous substrates, on mobile screes, stony slopes and rocky debris, between 1800 and 2450 m above sea level.

Generic name (Isatis): Derived from the Greek isazo. According to Dioscorides it recalled the idea of “smoothing”, in reference to the abrasive or healing properties of some species; for Tournefort it instead meant “to make whole”, alluding to adhesive qualities. This genus is historically known for woad, from which indigo-blue pigment was extracted. Specific name (apennina): A geographical adjective identifying the Apennines as the characteristic range of this plant.

Allioni’s woad is considered a rare species because of its strong habitat specialization. Its survival is tied to the stability of high-altitude screes, fragile environments easily affected by climate change and excessive trampling. Because of its rarity and biogeographical value, it has been included in several Regional Red Lists as a protected or specially monitored species.