Sicydium, Schlechtendal, 1832

Nicola, Marcela V., Donadío, Sabina & Pozner, Raúl, 2015, A new species of Sicydium (Cucurbitaceae) from Argentina, Phytotaxa 197 (2), pp. 153-156 : 155-156

Key to identify species of Sicydium based on material with staminate flowers

The following key was based on Lira (2004) and modified to include Sicydium nereoi , S. gracile , and S. diffusum . The main diagnostic characters of Sicydium species are found in the staminate flowers and pubescence. Carpellate flowers do not possess characters to discern the species ( Lira 2004), probably because material with carpellate flowers and fruits is rare. In fact, those structures are not known for Sicydium davilae , S. nereoi , and S. difussum (cf. Cogniaux 1878, Porto 1974, Lira 2004).

1. Pedicels of the staminate flower articulate at some point on the upper, distal half............................................................................2

1. Pedicels of the staminate flowers articulate at some point on the lower, proximal half....................................................................6

2. Plants glabrous (only the pedicels pubescent), filaments 1–1.5 mm long.............................................................. Sicydium diffusum

2. Plants pubescent, if glabrous, with filaments no longer than 0.7 mm ..................................................................................................

3. Pedicels articulated just under the flower.................................................................................................................. Sicydium gracile

3. Pedicels articulated in between the staminate flower and the middle point.......................................................................................4

4. Plant glabrous or slightly puberulent, trichomes usually shorter than 1 mm, leaves always entire, surface frequently shiny on both sides ...................................................................................................................... Sicydium schiedeanum Schlechtendal (1832: 388)

4. Plants noticeable puberulent, pubescent, tomentose or sometimes woolly, at least on the abaxial side of leaves, trichomes 1–3 mm long, easy to see, leaves entire, angulose or slightly lobate-lobulate, surface never shiny................................................................5

5. Stems puberulent to noticeable pubescent, leaves puberulent and rough-scabrose on the adaxial side, and smooth pubescent to tomentose on the abaxial side, indumenta made of glandulose and eglandulose trichomes, usually dark brown, reddish or sometimes greenish when dry................................................................................................... Sicydium tuerckheimii Donnell Smith (1911: 49)

6. Pedicels articulated at the base (no pedicel remains on the cyme peduncle after flower senescence), pedicels glabrous. Filaments as long or twice the length of the anther, connective usually widened or divaricate ................................................. Sicydium nereoi

6. Pedicels articulated at some point on the lower, proximal half (part of the pedicels remain on the cyme peduncle after flower senescence), pedicels puberulent-glandulose, connective narrow or very much reduced.................................... Sicydium tamnifolium