Begonia sizemoreae Kiew

Kiew, Ruth, 2007, Notes on Vietnamese Begonia (Begoniaceae), including three new species, Adansonia (3) 29 (2), pp. 229-238 : 234

4. Begonia sizemoreae Kiew

Gardens Bulletin Singapore 56: 95 (2004).

Begonia rex auct . non Putz.: Gagnepain in Lecomte, Flore générale de l’Indo-Chine 2: 1112 (1921).

MATERIAL EXAMINED. — Mt Ba Vi , Son-gi Village, XII.1887, Balansa 3765 ( P).

REMARKS

Gagnepain (1921) based his description of Begonia rex on Balansa 3765 (P). This specimen is typical of B. sizemoreae in its leaves that have densely hairy petioles and laminas that are more rounded than those of B. rex (the difference in leaf shape between these two species is clearly shown in Tebbitt 2005: pl. 89), and that have a very hairy leaf margin, hairy upper surface of the lamina with hairs 5-10 mm long and have conspicuous deep crimson tertiary venation in the centre and outer part of the lower leaf surface – this last feature can be seen even in the dried leaf.

Balansa 3765 is a well-grown specimen (its laminas measure 14 × 14.5 cm), which necessitates some modification to the original description in Kiew (2004) and also enables description of the fruit. The ratio of petiole to lamina length is variable, i.e. longer or shorter than the lamina and there is also variation in whether the basal lobes of the lamina overlap or not (this can vary even on the same plant); and the inflorescence is either monochasial or dichasial (the latter is seen in the Balansa specimen that has four fruits on a single infructescence). These characters therefore cannot be used to distinguish B. sizemoreae from B. rex .

The fruit is the typical splash cup of sect. Platycentrum : the capsules are (8-) 15-18 mm long and (23-) 30-37 mm wide with pedicels 13-20 mm long and the large fibrous wing is 17-25 mm wide and the two shorter, thinner wings (5-) 7-9 mm wide. The tips of the wings are rounded.

Begonia sizemoreae is one of the most beautiful Vietnamese begonias and it is becoming popular in cultivation ( Kiew 2004). Hô. (1991, 1999) correctly noted Begonia rex Putz. only as cultivated in Vietnam. Begonia rex should therefore be excluded from the list of indigenous Vietnamese species.

DISTRIBUTION

Endemic in Vietnam, known only from Hà Tây (Mont Ba Vi).

B. NAMES EXCLUDED FROM THE BEGONIA FLORA

OF VIETNAM