TRUFAMANIA

Pasion por la trufa

Species index

DESERT TRUFFLES

What are desert truffles? The term “desert truffles” refers to edible hypogeous fungi — fungi that complete their entire life cycle underground — that grow in the arid and semi-arid areas of the Mediterranean region, belonging to the genera Delastria, Picoa, Terfezia, Tirmania, Mattirolomyces, Loculotuber and Tuber.

 

Terfezia claveryi

 

Desert truffles are highly prized in Arab countries and can be found in Moroccan markets under the common name terfass (also spelled terfess or terfez). They are harvested almost entirely in spring, with the exception of Delastria rosea and Tuber oligospermum, which ripen in November and December. All desert truffle genera grow naturally in Spain except Tirmania, but only three Terfezia species are harvested in commercially significant quantities: T. arenaria, T. claveryi and T. fanfani. Common names vary by region; the most frequent are “turmas” in Murcia, “patatas de tierra” and “criadillas de tierra” in Extremadura, “papas crías” in Lanzarote and “criadas” in Fuerteventura. In addition to these terfezias, Picoa species are traditionally consumed in Spain, though their small size makes them unsuitable for commercial trade. They are known locally as “negrillos” and “monegrillos”.

 

Picoa juniperi

 

Are they true truffles? The Romans knew desert truffles and called them “tuber”, Latin for “hump” or “lump”, presumably because of the bulge they push up in the soil as they ripen. The word “truffle” derives from “tuber”. What we now know as true truffles — species of the genus Tuber — were discovered later and inherited the same name because they too grow underground. The term “truffle” is increasingly used to refer to all hypogeous fungi, and from that perspective desert truffles may reasonably be called truffles. However, the issue is essentially a commercial one: calling them truffles can mislead consumers. Gastronomically, desert truffles bear no resemblance to Tuber melanosporum, and their culinary use is entirely different. While true truffles are used to impart fragrance to dishes, desert truffles have no aroma and are eaten like any other mushroom.

What are terfezias? Terfezias are the most common desert truffles in Spain. They grow underground in symbiotic association with the roots of certain plants, generally Helianthemum.

The name comes from the Arabic “terfez”, used across North Africa as a collective term for all desert truffles. Terfezias have been known and appreciated since Antiquity; the Greeks and Romans already traded in them. Pliny called them “children of thunder” because harvests were more abundant following a rainy autumn with heavy storms.

As they approach maturity, terfezias swell and crack the surface of the ground, making them detectable to any observer with a keen eye. Although they grow in semi-arid climates, they require rainfall to develop, with the rains of August–September and January–February being particularly beneficial.

Terfezia arenaria and Terfezia fanfani are found in acid soils. Terfezia claveryi, Terfezia boudieri and Terfezia morenoi grow in alkaline soils.

 

Terfezia crack

 

NUTRITIONAL VALUE OF TERFEZIAS

Although desert truffles are consumed mainly by tradition and for their pleasant taste, they contain significant amounts of protein and notably high levels of antioxidants, making them of considerable nutritional interest. Their composition varies by species and across studies. The following table summarises the published data.

 

 

Terfezia albida

 

FULL DESCRIPTION Terfezia albida is a spring species that grows in alkaline soils, always associated with Helianthemum roots. So far we have only found it in Albacete and Murcia (Spain). White at first, becoming light beige, often with black spots on sun-exposed or handled surfaces, and developing greenish discolouration on cut or aged areas. Size 2–4 cm across, 3–4 cm high, subglobose to turbinate. Gleba white at first, maturing to greyish-green pockets of fertile tissue separated by whitish sterile veins. Spermatic odour, more noticeable in young specimens. Microscopy: Asci subglobose to ovate, 8-spored. Ascospores yellow ochre, spherical, 18–23 µm in diameter (including ornamentation), decorated with conical, blunt, straight spines, 2–3 µm long, 1–2 µm wide at the base, sometimes connected to form a pseudo-reticulum.

Terfezia arenaria

 

FULL DESCRIPTION Terfezia arenaria is a spring species that grows in acid, sandy, moist soils poor in organic matter, always associated with Tuberaria guttata roots, locally known as the “criadilla mother”. Potato-shaped, 3–10 cm in size. Thick peridium, white at first, dark brown at maturity. The gleba is whitish at first, becoming pink with pale veins. Mild smell and taste. Microscopy: asci globose to subglobose, 8-spored. Ascospores yellow ochre, spherical, 25–30 µm in diameter (including ornamentation), decorated with truncated warts up to 7 µm tall.

Widely distributed across the western half of the Iberian Peninsula. Very common in the grasslands of Extremadura, where it is known as “criadilla de tierra” and “patata de tierra”. Gastronomically prized. Sold fresh and canned in Extremadura, where it has long been a traditional food.

Terfezia boudieri

 

FULL DESCRIPTION Terfezia boudieri is a spring species that grows in alkaline soils, always associated with Helianthemum roots. We have found it only in the Canary Islands, associated with Helianthemum canariense, and in Murcia with Helianthemum almeriense. Potato-shaped, 2–6 cm in size, fairly regular and rounded to pyriform. Thick peridium, dark brown to blackish at maturity, never showing the vivid colours seen in T. claveryi. Specimens are often cracked. The gleba is salmon pink at maturity with paler veins, sometimes turning yellowish-orange on exposure to air. Microscopy: asci subglobose, ovoid, somewhat polymorphic, 4–6-spored. Ascospores yellow ochre, spherical, 20–25 µm in diameter (including ornamentation), decorated with truncated and hemispheric warts up to 2 µm tall, with conical spines at maturity, interconnected at the base to form a low reticulum that is most apparent in young specimens before the warts are fully developed.

We have harvested Terfezia boudieri together with Terfezia claveryi and Picoa lefebvrei, sharing both habitat and ripening period.

Terfezia canariensis

 

FULL DESCRIPTION Terfezia canariensis is a spring species that grows in alkaline soils, always associated with Helianthemum canariense roots. So far we have only found it in the Canary Islands, in calcareous soils — both clayey inland soils and coastal sands. Terfezia canariensis was long confused with Terfezia claveryi, but molecular, ecological and microscopic studies have allowed both species to be clearly distinguished.

Terfezia cistophila

 

FULL DESCRIPTION Terfezia cistophila is a spring species that grows in acid soils, associated with Cistus spp. So far we have only found it in Extremadura (Spain) and Greece. Ascomata 0.5–2 cm in size, subglobose, light beige at first, becoming dark reddish brown with black spots. Gleba whitish with greyish fertile pockets at first, maturing to light ochre, separated by whitish sterile veins. Spermatic odour, more noticeable in young specimens. Microscopy: Asci subglobose to ovate, 8-spored. Ascospores yellow ochre, globose, 17–20 µm in diameter (including ornamentation), ornamented with conical, separate, pointed, sometimes truncated spines, 1.5–2.5 µm long, 1 µm wide at the base.

Terfezia claveryi

 

FULL DESCRIPTION Terfezia claveryi is a spring species that grows in alkaline soils, always associated with Helianthemum spp. Widely distributed across the eastern half of the Iberian Peninsula. More irregular in shape than T. arenaria — often flattened, lobed or pyriform with a tapered sterile base — because it grows in more compact soils; specimens from sandy, loose soils tend to be rounder and more regular. Size 3–12 cm. Thick peridium, dark reddish brown at maturity. Gleba whitish at first, becoming salmon pink with paler veins, sometimes turning yellowish-brown on exposure to air. Microscopy: asci globose to ovoid, 8-spored. Ascospores yellow ochre, spherical, 18–21 µm in diameter (including ornamentation), decorated with hemispheric warts up to 2 µm tall and 2–3 µm wide, forming a well-developed reticulum that is most apparent when warts are low.

T. claveryi is widely eaten in Murcia, where it is known as “turmas”, and in Albacete. Gastronomically prized and considered more flavourful than T. arenaria. Harvests are highly variable and strongly dependent on rainfall; in dry years the “turmas” may not appear at all.

Terfezia eliocrocae

 

FULL DESCRIPTION Terfezia eliocrocae is a spring species that grows in alkaline soils, always associated with Helianthemum spp. So far we have only found it in Albacete and Murcia (Spain), and only in small numbers. Size 3–7 cm. Gleba white and friable. Very faint odour and taste. Microscopy: asci pyriform, 8-spored. Ascospores ochre, globose, 16–18 µm in diameter (including ornamentation), reticulate.

Terfezia extremadurensis

 

FULL DESCRIPTION Terfezia extremadurensis is also a spring species, but appears earlier than T. fanfani and can be found from January in Extremadura. It grows in acid, sandy soils, associated with Tuberaria guttata roots. Cream-coloured at first, becoming pale ochre. The gleba is whitish at first, then greenish grey at maturity, marbled with thin, white, meandering veins. Often shows small holes indicating mycophagous activity. Mild smell and taste. Microscopy: asci subglobose, 8-spored. Ascospores yellow ochre, spherical, 21–27 µm in diameter (including ornamentation), decorated with conical, blunt, thick spines, sometimes truncated or finger-like, often joined at the base, 3–4(–5) µm long, 1–3 µm wide at the base. Widely distributed across the western half of the Iberian Peninsula. Very common in Extremadura, where it is known as “criadilla de tierra”, “patata de tierra” and “blanquilla”.

Terfezia fanfani

 

FULL DESCRIPTION Terfezia fanfani is also a spring species, but appears earlier than T. arenaria and can be found from January in Extremadura. It grows in acid soils, both sandy and more compact. Associated with Tuberaria guttata roots. Similar in appearance to T. arenaria, but smaller and more reddish. Peridium thin and reddish from an early stage, slightly rough. The gleba is whitish at first, becoming greenish grey with whitish veins. Mild smell and taste. Microscopy: asci subglobose, 8-spored. Ascospores yellow ochre, spherical, 19–22 µm in diameter (including ornamentation), decorated with conical, very sharp, isolated spines up to 5 µm tall. Widely distributed across the western half of the Iberian Peninsula. Very common in Extremadura, where it is known as “criadilla de tierra”, “patata de tierra” and “rojilla”. Gastronomically prized; some consider it more flavourful than T. arenaria.

Terfezia grisea

 

FULL DESCRIPTION Terfezia grisea is a spring species that grows in alkaline soils, associated with Helianthemum spp. Ascomata 1–2.5 cm in size, subglobose, pale rusty at first, becoming brownish to blackish. Gleba whitish with greyish pockets at first, maturing to blackish-grey pockets of fertile tissue separated by whitish sterile veins. Microscopy: Asci subglobose to ovate, 8-spored. Ascospores yellow ochre, globose, 19–21 µm in diameter (including ornamentation), ornamented with conical, sometimes truncated, separate, blunt spines, 2–3 µm long, 1–2 µm wide at the base.

Terfezia morenoi

 

FULL DESCRIPTION Terfezia morenoi is a winter-spring species associated with the roots of pines and holm oaks, without the presence of Helianthemum. It is a little-known Terfezia, long confused with Terfezia leptoderma — and regarded as a synonym by some authors — but the two are clearly separated by their different ecology and microscopy. Little is known about its distribution. We have found it in Murcia and Albacete. Globose, fairly regular, 2–5 cm in size. Thin peridium, whitish at first, becoming brown and blackening on handling. The gleba is pinkish grey, then becoming olive green with pinkish-white veins. Microscopy: asci subglobose to ovoid, 8-spored. Ascospores ochre, spherical, 16–19 µm in diameter (including ornamentation), decorated with isolated conical spines, 1–2 µm tall (shorter and less dense than those of T. fanfani).

Tirmania nivea

 

Tirmania nivea is the true desert truffle and the most highly prized in Arab countries. It can be found in markets from January to April. It grows wild in the deserts of North Africa, from Morocco to Iraq. Its most common name is “zubaidi”, though it is also known as “fagaa” — the collective term for all desert truffles in the Persian Gulf countries — and as “terfez” in Morocco.

Tirmania nivea, known and consumed since Antiquity, is likely the truffle referred to by Greek and Roman writers. The Roman poet Juvenal wrote in his satires: “Keep your grain, O Libya!… unyoke your oxen if only you send truffles!”. Elinoar Shavit and Tom Volk have suggested it may have been the manna that sustained the Israelites during their crossing of the desert.

Tirmania nivea habitat

White when extracted from the ground, Tirmania nivea quickly turns yellowish on exposure to air. It is very fleshy and can exceed 10 cm in diameter. The gleba is whitish or pale pink with paler veins. The smell and taste are mild and fungal.

Microscopy: amyloid asci and smooth spores.

Tirmania nivea grows in desert sand, associated with Helianthemum roots.

Its price in Arab markets rarely exceeds €40 per kg, though this depends greatly on the harvest. In very dry years, the “white desert truffle” can reach €200 per kg. In Europe, Tirmania nivea is sometimes marketed as Italian white truffle (Tuber magnatum) owing to a superficial resemblance, and may be offered at exorbitant prices entirely out of proportion with its gastronomic value.

 

Picoa juniperi

 

Picoa juniperi is a spring species associated with Helianthemum roots, sharing habitat with T. claveryi but with a considerably wider distribution. We have found it in Albacete, Madrid and Teruel; it is recorded throughout calcareous areas of Spain, though some records have since been reassigned to Picoa lefebvrei.

Picoa juniperi

We believe that Picoa juniperi and Picoa lefebvrei are the same species.

Ascoma: subglobose, fairly regular, 1–3 (5) cm in size. Peridium warted, black, covered with flattened, polygonal, umbilicate warts. These warts are not always as small as described in some publications — we have observed warts up to 4 mm wide — and these Picoas can resemble summer truffles externally. Gleba white with white veins. Sweet, coconut-like smell and pleasant taste. Microscopy: asci subglobose, with 6–8 spores. Ascospores hyaline, spherical (some slightly ellipsoid), with a large guttule, smooth, becoming finely punctate at maturity, 22–28 (32) × 22–25 (28) µm (Q=1.00–1.16).

Common names include: “chivatos de las turmas” in Murcia and “negrillos” and “monegrillos” in Albacete. Picoas are eaten together with terfezias, but their small size makes them unsuitable for commercial trade.

 

Picoa lefebvrei

 

Picoa lefebvrei is a spring species associated with Helianthemum roots, sharing habitat with T. claveryi but with a wider distribution owing to its less demanding soil requirements. We have found it in Albacete and Murcia. Its distribution is poorly understood due to confusion with Picoa juniperi (which we consider the same species).

P. lefebvrei parasitized by Melanospora zobelii

Ascoma: subglobose, fairly irregular when several specimens grow together — the most frequent situation — 1–3 (5) cm in size. Light brown, darkening to very dark brown or blackish at maturity, sometimes with reddish tones. Surface covered with very small (1–2 mm wide), flattened, umbilicate warts of more or less regular distribution. Young specimens are often coated with a brown tomentum that fades with age. Gleba white with white veins. Sometimes parasitised by Melanospora zobelii, which appears as black dots in the gleba. Sweet, coconut-like smell and pleasant taste. Microscopy: asci subglobose to ellipsoid, 4–8-spored. Ascospores hyaline, spherical to broadly ellipsoid, with a large central guttule, smooth, becoming finely punctate at maturity, 20–28 × 19–24 µm (Q=1.00–1.27). The spores appear identical to those of Picoa juniperi. Peridium pseudoparenchymatous with brown, long (>100 µm), pluriseptate, thick-walled (1 µm) hairs, 8–11 µm wide.

Common names include “chivatos de las turmas” in Murcia and “negrillos” and “monegrillos” in Albacete, where they are also said to appear before the terfezias. Consumed together with Terfezia claveryi, but not commercially traded due to their small size.

 

Tuber gennadii

 

FULL DESCRIPTION Basionym: Terfezia gennadii Chatin 1896. Loculotuber gennadii is a spring species that grows in acid soils, associated with Tuberaria guttata and other Cistaceae roots, sharing habitat with Terfezia spp. It is a little-known species, frequently confused with Tuber asa, which some authors treat as a synonym, though the two are clearly separated by their microscopy. Its distribution is poorly known owing to this confusion. We have found it in Extremadura, Madrid and Albacete. Ascoma: subglobose, lobed, deeply sulcate, 1–5 cm in size. Thin peridium, dirty white becoming light brown. Gleba whitish at first, then brownish at maturity, marbled with thin white veins, friable, with small cavities visible. Odour strong, characteristic and distinctive. Microscopy: asci ellipsoid, long-stalked, more or less arranged among paraphyses, with 1–3 (4) spores. Ascospores yellow-brown, translucent, subglobose to broadly ellipsoid, citri- or eye-shaped, reticulate-alveolate, 28–40 × 27–40 µm (Q=1.00–1.37). Considerable variation in spore shape has been observed across collections, with some showing very few eye-shaped spores.

The genus Loculotuber was erected on the basis of the partially ordered arrangement of asci and paraphyses. This character is also highly variable and is most easily observed when the gleba contains more cavities.

Known locally in Extremadura as “requesón” (cottage cheese). Edible but of little gastronomic interest and generally discarded.

Tuber melosporum

 

FULL DESCRIPTION Tuber melosporum is a Tuber species associated with Helianthemum spp. and Quercus ilex in the original description by Moreno et al. (2000), but it has also been found under Pinus halepensis in the absence of Helianthemum. Ascoma: 1–3 cm in size, subglobose. Peridium dark brown to almost black with reddish tones, surface covered with flattened, irregular warts giving a cracked appearance. Gleba brown, marbled with white aeriferous veins and dark parallel veins. Microscopy: Asci ovoid to elongated pyriform, 70–90 × 50–60 µm, with a long stalk up to 60 µm, containing 1–4 (5) spores. Ascospores 26–50(–58) × 17–30 µm, Q=1.24–1.82, size highly variable depending on the number of spores per ascus; ellipsoid, smooth, hyaline at first, yellow ochre at maturity, with a very thick wall (2 µm). Peridium 200–350 µm thick, composed of agglutinated, interwoven hyaline hyphae that become pseudoparenchymatous and pigmented brown towards the surface, corresponding to the warts. Notes: the peridium microscopy and ascus shape are very similar to the Tuber rufum group, as is the macroscopic appearance.

 

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Antonio Rodríguez trufamania@gmail.com antonio@trufamania.com