2.3 Grape Varieties & Ampelography

Ampelography, Grape Genetics & Varietal Typology

Core Sommelier Competency: For the CMS Certified Sommelier examination, sommeliers must demonstrate command over grapevine taxonomy, understand how ampelographers identify varieties in the vineyard, trace key genetic parentages, distinguish between clonal and mass selection, and map varieties to their climatic requirements and primary chemical aroma drivers.

Ampelography (from the Greek ampelos, meaning 'vine', and graphos, meaning 'description') is the botanical discipline concerned with the identification, description, and classification of grapevine species and cultivars. Founded scientifically in the 20th century by French ampelographer Pierre Galet, it combines visual morphological analysis with modern DNA microsatellite profiling (spearheaded by Dr. Carole Meredith at UC Davis).

1. Botanical Taxonomy of the Grapevine

All commercial wine grapes belong to the botanical hierarchy:

• Kingdom: Plantae
• Family: Vitaceae (approx. 14 genera of woody climbing vines)
• Genus: Vitis
  • Subgenus Muscadinia (40 chromosomes): e.g., Vitis rotundifolia (Muscadine / Scuppernong native to Southeastern US).
  • Subgenus Euvitis (38 chromosomes): Contains over 60 distinct species, including:
    • Vitis vinifera: The Eurasian grapevine responsible for 99% of fine wine. Originating in the Transcaucasus (Georgia, Armenia, Eastern Turkey) ~6000–8000 BCE. Estimated 5,000–10,000 cultivated varieties.
    • Vitis labrusca: Eastern North American 'Fox grape' (Concord, Catawba, Niagara). Exhibits pungent foxy aroma from methyl anthranilate.
    • Vitis riparia, Vitis rupestris, Vitis berlandieri: North American species used globally as phylloxera-resistant rootstocks.
    • Vitis amurensis: Cold-hardy Asian wild species capable of surviving -40°C winter freezes.

2. Ampelographic Identification Criteria

Ampelographers identify grape varieties in the vineyard by examining specific morphological structures at defined phenological stages (primarily spring shoot tips and summer mature leaves).

 Key Morphological Points of Ampelographic Identification:
 1. Shoot Tip (Apex): Open vs. closed; felty/cottony hair density; presence of bronze/anthocyanin pigment.
 2. Mature Leaf Blade: General shape (pentagonal, orbicular, wedge, kidney); number of lobes (3, 5, 7);
    depth and shape of lateral sinuses (U-shaped, V-shaped, lyre-shaped, overlapping).
 3. Petiolar Sinus: The opening where the leaf stalk (petiole) meets the blade (open V, lyre, closed/overlapping).
 4. Cluster Morphology: Conical, cylindrical, winged, shouldered; loose/airy vs. tight/compact.
 5. Berry Morphology: Spherical, oval, elliptic; skin thickness; color of exocarp bloom.

Famous Historical Ampelographic Misidentifications

Modern ampelography and DNA testing have solved numerous historical identity confusions:

1. Carmenère in Chile: For over a century, Chilean growers believed their premier red plantings were a late-ripening clone of Merlot ('Merlot Tardif'). In 1994, French ampelographer Jean-Michel Boursiquot identified the vines as Carmenère—a historic Médoc variety thought extinct after phylloxera—by observing its distinct twisted petiolar sinus and reddish, carmine-hued young shoot tips.
2. Zinfandel / Primitivo / Crljenak Kaštelanski: Long claimed as a native California variety, DNA profiling by Dr. Carole Meredith in 2001 proved that Zinfandel is genetically identical to Puglia's Primitivo and Croatia's ancient indigenous variety Crljenak Kaštelanski (also known as Tribidrag).
3. Bonarda in Argentina vs. Italy: The widely planted 'Bonarda' of Argentina was revealed through DNA testing to be the Savoie variety Corbeau (known as Charbono in California), completely unrelated to the Bonarda of Piedmont (Bonarda Piemontese) or Croatina in Lombardy.
4. Sauvignonasse / Friulano in Chile: Much of what was planted as Sauvignon Blanc in Chile prior to the 1990s was actually Sauvignonasse (Friulano).

3. Vine Propagation & Genetic Variation

Grapevines reproduce either sexually or asexually. The method selected determines whether genetic identity is preserved or altered.

 Methods of Grapevine Propagation:
   +-------------------------------------------------------------------------+
   | SEXUAL PROPAGATION (Seeds / Pips)                                       |
   | - Highly heterozygous: Each seed produces a completely novel variety.   |
   | - Used exclusively in viticultural research to create crosses & hybrids.|
   +-------------------------------------------------------------------------+
   | ASEXUAL PROPAGATION (Vegetative Cloning)                                |
   | - Preserves exact genetic DNA of the mother vine.                       |
   |   +--> 1. Clonal Selection: Single isolated mother vine propagated.     |
   |   +--> 2. Mass Selection (Sélection Massale): Diverse cuttings from parcel.|
   |   +--> 3. Layering (Marcottage / Provignage): Rooting living shoot in dirt. |
   +-------------------------------------------------------------------------+

1. Sexual Propagation & Breeding Classifications

• Intraspecific Crossing: A cross between two distinct varieties of the same species (Vitis vinifera × Vitis vinifera).
  • Cabernet Sauvignon = Cabernet Franc × Sauvignon Blanc (spontaneous natural cross occurring in 17th-century Bordeaux; confirmed by Bowers & Meredith in 1997).
  • Syrah (Shiraz) = Dureza (obscure dark grape from Ardèche) × Mondeuse Blanche (white grape from Savoie).
  • Pinotage = Pinot Noir × Cinsault (created in 1925 by Prof. Abraham Perold in South Africa).
  • Müller-Thurgau = Riesling × Madeleine Royale (bred in 1882 by Dr. Hermann Müller).
  • Petite Sirah (Durif) = Syrah × Peloursin (bred by François Durif in 1880).
  • Scheurebe = Riesling × Bukettrebe (bred by Georg Scheu in 1916).
• Interspecific Hybrid: A cross between two different botanical species (e.g., Vitis vinifera × Vitis riparia or Vitis labrusca).
  • Examples: Seyval Blanc, Vidal Blanc, Chambourcin, Baco Noir, Marechal Foch, Concord.
  • Regulatory Note: Interspecific hybrids are generally banned or strictly limited in classic European Protected Designation of Origin (PDO/AOC) appellations due to non-vinifera aroma characteristics.
• Clonal Mutation (Chimeric Mutation):
  • Spontaneous genetic mutations occur within dormant buds over centuries. The Pinot family is the premier example: Pinot Noir, Pinot Gris, Pinot Blanc, and Pinot Meunier share the same foundational DNA profile; their distinct colors and foliar textures result from simple somatic mutations affecting anthocyanin expression and epidermal hair density.

2. Asexual Propagation: Clonal vs. Mass Selection

4. Phenological Adaptations & Aroma Chemistry

Cultivars are categorised by their phenological timing (when they bud and ripen) and their signature chemical aroma compounds.

Phenological Ripening Windows

• Early Budding / Early Ripening: Varieties that break bud early in spring and achieve full physiological ripeness in short, cool growing seasons.
  • Cultivars: Chardonnay, Pinot Noir, Merlot, Tempranillo (from Spanish temprano, meaning 'early'), Gamay, Sauvignon Blanc.
  • Climatic Fit: Cool continental and maritime regions (Champagne, Chablis, Burgundy, Mosel, Willamette Valley).
  • Vulnerability: Highly susceptible to early spring radiation frosts on tender buds.
• Late Budding / Late Ripening: Varieties that require high cumulative thermal energy (Winkler Region III–IV) and long, warm autumns to break down acids and polymerize tannins.
  • Cultivars: Cabernet Sauvignon, Nebbiolo, Syrah, Grenache, Mourvèdre, Carignan, Sangiovese, Touriga Nacional.
  • Climatic Fit: Warm Mediterranean and semi-arid climates (Southern Rhône, Priorat, Barolo, Napa Valley, Barossa Valley).
  • Vulnerability: In cool climates, late autumn rains cause grey rot before sugars and phenolic tannins reach maturity.

Key Varietal Aroma Chemical Families