Rhododendron citrinum (Hassk.) Hassk., Cat. Hort. Bot. Bog. Alt.

Mambrasar, Yasper Michael, Warseno, Tri, Kuswantoro, Farid & Arifiani, Deby, 2024, NOTES ON RHODODENDRON (ERICACEAE) FROM BALI, INDONESIA, AND A NEW SUBSPECIES OF RHODODENDRON JAVANICUM, Edinburgh Journal of Botany 81 (1962), pp. 1-11 : 3

1. Rhododendron citrinum (Hassk.) Hassk., Cat. Hort. Bot. Bog. Alt. , 161 (1844). – Azalea citrina Hassk., Flora 25(2, Beibl. 1): 30 (1842). – Type: Indonesia, Java, Mt Gede , Tjibeureum , 31 xii 1924, Docters van Leeuwen 8245 (neotype BO [157586] designated by Sleumer [1960]).

Rhododendron zippelii Blume, Fl. Javae, Pl. Ined. : t. 4 (1863–1883). – Type: Indonesia, Java, Megamendung, Zippel s.n. (holotype L).

var. citrinum

Shrub. Twigs 1–2 mm in diameter, rounded, covered by brown scales; internodes

50–80 mm. Leaves 5–8 in tight pseudowhorls, 17–48 × 6–18 mm, broadly elliptic, narrowly elliptic to elliptic, apex obtuse, broadly acute, margin narrowly revolute, base broadly tapering, densely scaly, quickly glabrescent above, persistently scaly beneath. Scales flat, small, subdendroid and scattered. Petiole 4–10 mm long, grooved, densely scaly. Flowers

2- to 5-clustered, half hanging. Pedicels 14–21 mm long, scaly. Corolla 10–12 mm long,

7–8 mm in diameter, campanulate, pale yellow to yellowish white, outer surface densely scaly, inner surface glabrous, stamens glabrous, c.3 × 1 mm, oblong, ovary 3 × 2 mm, laxly scaly, style glabrous. Fruit 10–20 × 3–4 mm, cylindrical.

Distribution. Java and Bali. In Bali only known from Mount Abang.

Habitat and ecology. Epiphyte in montane forests 1600–1800 m a.s.l.

Proposed IUCN conservation category (Bali). Globally assessed as Least Concern (LC) ( Argent, 2015). In Bali, it is known only from a single specimen in BO from Mount Abang, collected by van Steenis (8033) in 1936. This mountain is a popular area for climbers and as a place of worship for Balinese Hindus. The area is in danger of being damaged by the planned construction of a cable (Suyasa, 2022). Its small population size and plausible future threats from development activities suggest a provisional assessment of Vulnerable (VU) D2 (IUCN Standards and Petitions Subcommittee, 2022).

Notes. Misapplied name: Rhododendron jasminiflorum (auct. non Hook.) Koord., Junghuhn Gedenkb. 184 (1910); Hallier f., Med. Rijksherb. 1: 35 (1910).

Additional specimen examined. INDONESIA. Bali: Mt Abang , 1600–1800 m, 9 iv 1936, C. G. G. J. van Steenis 8033 ( BO) .