Luehea Willd., Neue Schriften Ges. Naturf. Freunde Berlin

Gerace, Samuele, Peruzzi, Lorenzo, Baumgratz, José Fernando A. & Bovini, Massimo G., 2025, Flora of Rio de Janeiro: the genus Luehea (Malvaceae: Grewioideae), Rodriguesia (e 00512024) 76, pp. 1-13 : 2-3

Luehea Willd., Neue Schriften Ges. Naturf. Freunde Berlin 3: 409. 1801.

= Alegria Moc. & Sessé ex DC, Prodr. [A. P. de Candolle] 1: 516. 1824.

= Brotera Vell., Fl. Flumin. : 322. 1829.

Sh r ubs to t rees; bra nc hes c yl i nd r ica l, glabrous, with white longitudinal streaks, young twigs and petioles densely tomentose with brown stellate trichomes; stipules caducous, lanceolate. Leaves simple, alternate, petiolate; leaf blades membranaceous to coriaceous, elliptic, ovate, oblong, obovate or lanceolate, base cuneate, rounded or subcordate, apex acute, margin serrate, trinervate, basal nerves extending twothirds to three-fourths length of the blade; adaxial surface green, with sparse or dense stellate trichomes to glabrescent, abaxial surface white, with arachnoid trichomes and sparsely or densely stellate trichomes. Inflorescences many flowered, rare single flower, terminal to axillary, compound panicles; branches tomentose with stellate trichomes; pedicel tomentose, usually with two bracts caducous. Epicalyx with 6–12 bracteoles, linear, lanceolate, ovate or narrow-lanceolate, free, brownish, both surfaces tomentose, trichomes stellate. Sepals 5, lanceolate to ovate, usually revolute, abaxial surface with trichomes stellate, adaxial glabrous. Petals 5, white, yellow or pinkish, linear, obovate, orbicular, oblong or elliptic, margin entire or repand, with thickened basal nail, glabrous, base with appressed white trichomes. Androecium with five phalanges free or connate in a basal ring; staminodes in the external whorl, numerous, attached at the base of stamen phalange, connate or free, usually shorter than the stamens, sometimes equal or much longer, white villose at base; stamens numerous, free or connate, forming a tube around the style, villose at base; anthers dorsifixed, bilocular, thecae parallel, oblong, longitudinal dehiscence. Ovary 5-locular, superior, ovate, oblong, elliptic or globose, tomentose, transversal section angular, pentagonal or circular; style terete, completely or partially pubescent or glabrous; stigma capitate, glabrous. Fruit capsule loculicidal, ferruginous, brownish to blackish when adult, villose or tomentose, oblong, elliptic, narrow-elliptic, ovate, obovate, rhomboid or globose, apex cuspidate, cuneate, obtuse, acute, rounded or truncate, base acute, cuneate, rounded or truncate, glabrescent, 5-locular, partly dehiscent, dorsal surface valves convex, plane or sulcate, with central relief or not, valve margins plane or acute, crests-like or not. Seeds many, samaroid, glabrous, brown.

Key to the species of Luehea from the state of Rio de Janeiro

1. Single flower; staminodes much longer than the stamens; capsule with valve margins deeply acute, crest-like .............................................................................................................................................................. 2

1’. Inflorescence with 2 or more flowers; staminodes shorter or the same length as the stamens; capsule with valve margins plane, not crest-like ........................................................................................................ 3

2. Leaf blade 6–14.5 cm long; flower with diameter ≥ 6 cm, petals (3–5 cm long) longer than the sepals (2–3 cm long) and epicalyx bracteoles (1.5–3.7 cm long); capsule 3–4.5 cm long ............................... ................................................................................................................ 1. Luehea candicans var. candicans

2’. Leaf blade 1.8–5 cm long; flower with diameter ≤ 4 cm, petals, sepals, and epicalyx bracteoles of the same length (ca. 1.6 cm long); capsule ca. 2.5 cm long............... 1a. Luehea candicans var. gracilis

3. Petals entirely pinkish or with the base yellow; style 1/3-basal or 2/3-basal pubescent ..... 4

3’. Petals entirely white or yellow; style 1/2-basal or completely pubescent ............................... 5

4. Petals obovate; innermost stamens connate into a tube around the style; capsule ovate ....................................................................................................................... 3. Luehea divaricata

4’. Petals orbicular; stamens completely free; capsule elliptic, sometimes clavate................ ...................................................................................................................... 6. Luehea paniculata

5. Flowers with diameter> 4.5 cm; epicalyx bracteoles ≥ 1.6 cm long; petals ≥ 2.4 cm long; capsule on average longer ................................................................................... 6

5’. Flowers with a diameter ≤ 4 cm; epicalyx bracteoles ≤ 1.5 cm long; petals ≤ 1.7 cm long; capsule on average shorter ................................................................................... 7

6. Epicalyx bracteoles with base cuneate; ovary ovate to globular, circular to pentagonal in transversal section; capsule tomentose, with dorsal surface valve convex to plane .................................................................. 7. Luehea speciosa

6’. Epicalyx bracteoles with base cordate to rounded; ovary oblong to elliptic, angular in transversal section; capsule villose, with dorsal surface valve deeply sulcate .................................................................................... 4. Luehea macrophylla

7. Epicalyx bracteoles 1.1–1.5 cm long; petals yellow, obovate; style 1/2-basal pubescent or glabrous; capsule 1.8–2.5 cm long, obovate, tomentose, dorsal surface valve deeply sulcate without central relief ...................... ....................................................................................... 5. Luehea ochrophylla

7’. Epicalyx bracteoles 0.35–0.6 cm long; petals white, linear; style completely pubescent; capsule 1.2–1.7 cm long, elliptic to ovate, villose, dorsal surface valve deeply sulcate with central relief ..................... 2. Luehea conwentzii