The Medicinal Plant Walk is divided into several subsections that explain the evolution of the use of this natural resource throughout the history of pharmacology and medicine, as well as presenting a selection of medicinal plants from different regions of the world.

Medicinal rock garden.The walk begins, on its left-hand side when approached from the central pathway of the JBCLM, with a large rock garden that connects with the Gardens of the World section on the lower terrace. This rock garden mainly features native plant species that have traditionally been used in rural Castilla–La Mancha, collected directly from the wild, as well as some archaeophytes (plants introduced before 1492 and cultivated in the region for centuries). Species found here include strawberry tree (Arbutus unedo; diuretic), elder (Sambucus nigra; expectorant, diaphoretic and anti-inflammatory), bearberry (Arctostaphylos uva-ursi; diuretic and anti-inflammatory), broom (Retama sphaerocarpa; astringent and anti-inflammatory), wall germander (Teucrium chamaedrys; anti-inflammatory), violets (Viola odorata; relaxing and anti-inflammatory), service tree (Sorbus domestica; astringent), fig (Ficus carica; digestive, sweetening and diuretic), among others.

Medicinal climbers.Growing on the pillars of a large pergola opposite the medicinal rock garden, on the left-hand side of the walk, are climbing plants with medicinal properties, such as Akebia quinata, used as a diuretic and analgesic; ivy (Hedera helix), with stimulant, expectorant and healing properties; hop (Humulus lupulus), with sedative properties; false jasmine (Trachelospermum jasminoides), with antirheumatic properties; and grapevine (Vitis vinifera), traditionally used to treat venous insufficiency and as an antioxidant.

Garden of simples.Beyond the rock garden lies a series of beds arranged in aligned small squares, each cultivated with a single species possessing specific healing properties. This horticultural layout evokes the medieval “gardens of simples” or medicinal gardens (the precursors of botanical gardens), which were mainly cultivated in monasteries (hortus conclusus). A metal sculpture representing the historic book De Materia Medica by Dioscorides stands out in this garden. This vademecum, written around AD 65, describes the medicinal properties of some 600 plants, as well as minerals and animal products, and was translated into Spanish by Andrés Laguna in the 16th century. Plants in this section include houseleek (Sempervivum tectorum; anti-inflammatory), madder (Rubia tinctorum; emmenagogue), Madonna lily (Lilium candidum; analgesic) and the rare Moorish myrtle (Myrtus communis subsp. baetica; astringent, antiseptic and anti-inflammatory).

Industrial pharmacy.Continuing along the Dr Ramón y Cajal Walk, visitors encounter, on the right-hand side, the subsection dedicated to modern and industrial pharmacy. This area refers to one of the first industrial extractions of a plant-derived active principle, salicylic acid, obtained from willow bark. Large pots display plants currently used in industrial pharmacy, such as milk thistle (Silybum marianum; neuroprotective, hepatoprotective and anti-inflammatory), Italian arum (Arum italicum; diaphoretic and expectorant) and nettle (Urtica dioica; anti-inflammatory, hypotensive and analgesic), among others, as well as trees such as ginkgo (Ginkgo biloba; antioxidant and anti-inflammatory), yew (Taxus baccata; anticancer), horse chestnut (Aesculus hippocastanum; venotonic and anti-inflammatory) and willows (Salix; analgesic, antipyretic and antirheumatic).

Medicinal arboretum.On the left-hand side of the walk, opposite the industrial pharmacy collection, a series of beds has been established with medicinal flora from around the world, grouped by continent:Africa, with araar (Tetraclinis articulata; anti-inflammatory), Atlas cedar (Cedrus atlantica; analgesic and emmenagogue), tamarisk (Tamarix africana; astringent), among others;America, with black locust (Robinia pseudoacacia; anti-inflammatory), silver maple (Acer saccharinum; sweetener), etc.;Europe and the Mediterranean, with silver lime (Tilia tomentosa; sedative), bay laurel (Laurus nobilis; anti-inflammatory, tonic and flavouring), cypress (Cupressus sempervirens; antioxidant), service tree (Sorbus domestica; astringent), among others;Oceania, with eucalypts (Eucalyptus; expectorant and antiseptic) and Cordyline australis (antioxidant);Asia, with golden rain tree (Koelreuteria paniculata; antioxidant), bamboo (Phyllostachys aurea, P. nigra; anti-inflammatory and antispasmodic), ginkgo (Ginkgo biloba; antioxidant and anti-inflammatory), wintersweet (Chimonanthus praecox; antioxidant) and winged spindle (Euonymus alatus; anti-inflammatory and antitumour), among others.