Hydrangea peruviana Moric. ex Ser., Prodr. [A.P. de Candolle] 4: 14. 1830.

Samain, Marie-Stephanie, Granados Mendoza, Carolina & Martinez Salas, Esteban Manuel, 2021, On Hydrangea peruviana, an endangered species from Ecuador, and Hydrangea oerstedii, very common in Costa Rica and Panama, and seven threatened Central and South American Hydrangeas, which have been confounded with these, PhytoKeys 171, pp. 91-153 : 91

6. Hydrangea peruviana Moric. ex Ser., Prodr. [A.P. de Candolle] 4: 14. 1830. Figures 6 , 9 , 10 , 11

Cornidia peruviana (Moric. ex DC.) Small, North American Flora 22(2): 161. 1905.

Type.

Ecuador. "In Peruvia prope Huyaquaquil", ♀, fruits, J.A. Pavón s.n. [J.J. Tafalla s.n.] (holotype: G! [G00301424], isotypes: F!, MA! [MA-811940])

Description.

Root-climbing liana of up to 30 m high, up to 20 cm diameter, functionally dioecious; leaves decussate, coriaceous, petiole sulcate adaxially, clasping its branch, color reddish brown, densely pubescent with partially caducous, reddish simple and stellate hairs, 0.5-2 cm long, leaving a semicircular scar on the branch when leaves shed; lamina very slightly spoon-shaped (Figs 9C , 10A, B ), elliptic to slightly obovate, 7.5-12.8 cm long, 4.2-5.4 cm broad, base rounded to decurrent, sometimes asymmetric or very slightly cordate, apex acute to acuminate, rarely mucronate, leaf margin serrate to slightly dentate, venation brochidodromous, veins 6-10 pairs, adaxial leaf side with midvein and primary veins slightly protruding secondary veins marked, primary veins join to form submarginal vein, pubescent with small, stellate whitish pubescence, abaxially with protruding midvein and primary veins, sometimes with a few smaller less visible primary veins between the clearly visible primary veins, marked secondary veins, secondary and tertiary veins forming a reticulate network, connecting the primary veins, reddish brown, pubescent with small, stellate reddish hairs, especially on the veins, young leaves densely pubescent, acarodomatia numerous, present in axils of midvein and primary veins as well as axils of secondary veins, veins broadening the acarodomatia, consisting of a cavity, rarely with hairs; inflorescence axis densely pubescent with brownish stellate hairs (Fig. 11 ), 7-12 cm long, broadening towards the apex, with 3-4 opposite or decussate leaf or kataphyll pairs below the inflorescence, generally not deciduous, petiole 2-4 mm long, adaxially sulcate, lamina nearly orbicular to obovate, 1.3-4.2 cm long, 1.2-2.8 cm broad, densely pubescent, scars of 2 pairs of kataphylls present, apex of the inflorescence axis woody, cone-shaped, slightly quadrangular, elongated bract scars visible (Fig. 11 ), narrower at the top, 4-5 mm broad, 2-3 mm high in functionally female plants, male inflorescences not seen; inflorescence bracts not seen, inflorescences lateral, opposite, 1 pair of inflorescences per flowering branch, sometimes only one inflorescence developing (Fig. 10A,B ), flowering branch continues growing vegetatively very rapidly during inflorescence development, including additional branching, with up to 5 leaf pairs above the inflorescences and below the first branch, with kataphylls opposite the branches, with dense reddish stellate hairs, inflorescence umbellate, buds not seen, in flowering stage 4.5-10 cm diameter, 4-7 cm high, 3-7 main axes in functionally female plants, partial inflorescences cymes, secondary and tertiary inflorescence axes with dense reddish stellate hairs; enlarged marginal flowers always present (Figs 10 - 11 ), terminally placed in a cyme, 1.5-2 cm diameter, sepals 1-4, sepals with marked veins, remnants of 2 pistils visible, further characters not observed in detail, pedicel 1.2-2.4 cm long; male flowers not seen, (0-)1-1.5(-2) mm long in functionally female flowers, receptacle semiglobose in functionally female flowers, ovary inferior, calyx lobes 4, triangular, papyraceous, 0.25 mm long, 0.25 mm broad, petals not seen; functionally female flowers: hypanthium 1.5 mm broad, 1 mm high, 8 well-marked ribs, stamen scars visible but too small to detect a number, pistils 2, 0.2-0.3 mm long, enlarging up to 2-2.5 mm during fruit maturation, stigmas apically clavate and shortly penicellate; fruit a semiglobose capsule (Figs 10 , 11C ), apically with a revolute border, dark reddish brown, 1.5 mm high, 2 mm broad above, 3 mm diameter, opening between the two pistils to release seeds, seeds not seen.

Distribution.

Hydrangea peruviana is a rare species which is known from Ecuador only (Fig. 6 ). Apart from the type collection, it is only known of six collections since 1980, two of which were realized during the explorations in the framework of our revision of the Neotropical Hydrangeas . It was found in a primary mountain cloud forest flowering very high (about 30 m) in the tree canopy. The cloudy environment in combination with the height at which the specimens were flowering made them very difficult to spot, potentially being the reason why this species has been so rarely collected by botanists.

Habitat.

This species has been reported in rainforest and cloud forest at elevations between 682 and 1300 m.

Phenology.

This species has been collected with flowers and fruits in March and July. Only female plants have been observed. There are no collections known of male individuals.

Notes.

Since the revision by McClintock (1957), most of the species mentioned in this paper had been lumped in H. peruviana . Following the treatment of the genus Hydrangea for Ecuador by Freire-Fierro (2004), H. oerstedii was reduced to a variety of H. peruviana , consequently all species of the present study belonged to what was until recently considered as a species complex. However, based on our extensive study of herbarium specimens, including type material, and field observations, it became clear that H. peruviana is a very distinct taxon which can easily be recognized by the densely pubescent reddish brown leaves with an acute to acuminate, rarely mucronate, apex, a serrate to slightly dentate margin and many characteristically shaped acarodomatia.

In contrast to what might be expected because of its name, H. peruviana is not known from Peru, the type locality area of Guayaquil now being the second largest city of neighboring Ecuador, and this country´s main harbor. However, at the time of its collection in the late 18th century, modern-day Peru and most of Spanish-ruled South America belonged to the Viceroyalty of Peru.

As mentioned by Macbride (1938), it is generally accepted that their collections in the area that correspond with present-day Ecuador were not realized by Spanish botanists Ruiz and Pavón, but by their collaborator Juan José Tafalla.

According to our molecular study, Hydrangea peruviana is closely related to H. panamensis , the two of them unrelated to the other species of this study (Granados Mendoza et al. unpublished results).

Preliminary conservation status.

Although this species has an EOO of about 13,515 km2, it is Endangered according to the IUCN categories and criteria ( IUCN 2012), with an AAO of 20 km2, less than five locations, as well as an extensive reduction in both EOO and AOO because of habitat destruction and fragmentation.

Additional specimens examined.

Ecuador. Carchi: Camino Chical-Peñas Blancas-Tobar Donoso, colec. a 5 horas de camino, 1°0'N, 78°12'W, 6 Dec 1993, 1200 m, sterile, Freire-Fierro 2616 (AAU, QCA); Esmeraldas: environs of Lita, on the Ibarra-San Lorenzo R.R., 550-650 m, 11 Jun 1978, ♀, fruits, Madison et al. 5251 (F, QCA); Pichincha: km 87-84 old road Quito-Santo Domingo, 1200-1300 m, 21 Mar 1980, ♀, fruits, Dodson 9733 (MO); Los Ríos, Road Patricia Pilar-Montañas de Ila, km 18, N side of Torre de Bijagual, below antenas, 00°38'S, 79°17'W, 620-680 m, 28 Feb 1993, ♀, fruits, Øllgaard & Borchsenius 100686 (QCA, QCNE); Santo Domingo de los Tsáchilas: 5.3 airline Km SW of Corina Parral, 0°39'20.8"S, 79°17'27.7"W, 693 m, 11 Jul 2012, ♀, fruits, Granados Mendoza et al. 2012-111 (GENT, IEB, MEXU, QCNE); same data as preceding, 0°39'21.5"S, 79°17'29.2"W, 682 m, 11 Jul 2012, ♀, fruits, Granados Mendoza et al. 2012-112 (GENT, HOXA, IEB, MEXU, QCNE).

Figures

Figure 6. Distribution of Hydrangea goudotii and Hydrangea peruviana.

Figure 9. Hydrangea panamensis A plant growing along the stem of a Cecropia B infructescence with young and mature fruits, and enlarged marginal flowers. Hydrangea peruviana C stolons with adventitious roots and decussate leaves. A, B field images of collection Samain & Martinez 2012 - 063 C field image of collection Granados Mendoza et al. 2012 - 112.

Figure 10. Hydrangea peruviana A branch with inflorescence B branch with leaves seen abaxially and inflorescence C close up of infructescence with maturing fruits and enlarged marginal flowers. A, B field images of collection Granados Mendoza et al. 2012 - 111 C field image of collection Granados Mendoza et al. 2012 - 112.

Figure 11. Hydrangea peruviana. Infructescence with young fruits and densely pubescent apex of the inflorescence axis. Field image of collection Granados Mendoza et al. 2012 - 112.