Xylopia arenaria Engler, Bot. Jahrb. Syst. 34: 159. 1904.

Johnson, David M. & Murray, Nancy A., 2018, A revision of Xylopia L. (Annonaceae): the species of Tropical Africa, PhytoKeys 97, pp. 1-252 : 82-87

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Xylopia arenaria Engler, Bot. Jahrb. Syst. 34: 159. 1904.


12. Xylopia arenaria Engler, Bot. Jahrb. Syst. 34: 159. 1904. Figs 3H View Figure 3 , 21B, D, E, G View Figure 21


TANZANIA [ “Sansibarküstengebiet”]. Dar-es-Salaam Region, Dar-es-Salam, in parkartigem Buschgehölz des Sachsenwaldes auf Sandboden , Nov 1902, A. Engler 2173 (lectotype, here designated: B! [10 01153133]) .


Shrub or small tree up to 6 m tall, secondary branches drooping; bark gray, sometimes blotched with white, smooth. Twigs reddish brown to light gray, pubescent, the hairs 0.2-0.8 mm long, bark soon peeling and flaking in reddish brown strips, becoming glabrate; nodes occasionally with two axillary branches. Leaf with larger blades 3.4-7 cm long, 1.5-2.5 cm wide, chartaceous to subcoriaceous, concolorous to slightly discolorous, ovate to lanceolate-ovate, occasionally lanceolate, apex acute to obtuse, base broadly cuneate, rounded, or subcordate, short-decurrent on petiole, glabrous or with a few hairs on the midrib adaxially, appressed-pubescent abaxially; midrib plane or slightly raised adaxially, raised abaxially, secondary veins indistinctly brochidodromous, 7-12 per side, diverging at 50-70° from the midrib, these and higher-order veins plane or slightly raised on both surfaces; petiole 2.5-5 mm long, shallowly canaliculate, pubescent. Inflorescences axillary or from axils of fallen leaves, 1(-2)-flowered, pubescent; pedicels not pedunculate, 1.8-3.5 mm long, 0.7-1.3 mm thick; bracts 3, evenly spaced along pedicel, persistent, 0.5-1.6 mm long, ovate, semicircular, or crescent-shaped, the upper two often bilobed, apex obtuse to acute; buds ovoid-conic, apex obtuse or less frequently acute. Sepals erect to slightly spreading at anthesis, 1/3-1/2-connate, 2.2-2.5 mm long, 2.1-2.7 mm wide, coriaceous, ovate to broadly ovate, apex acute, pubescent abaxially. Petals pale orange-yellow, cream, or white, the inner petals purplish red or rose-colored inside at the base in vivo; outer petals erect at anthesis, 6.6-10.2 mm long, 2.7-3.2 mm wide at base, 1.8-2.0 mm wide at midpoint, coriaceous or a little fleshy, lanceolate, apex acute, densely puberulent except for glabrous basal patch adaxially, densely appressed-pubescent abaxially; inner petals geniculate at anthesis, with the apices bent sharply outward between the outer petals, 4.7-7.2 mm long, 1.8-2.7 mm wide at base, 0.8-1.2 mm wide at midpoint, slightly fleshy, lanceolate-acuminate, apex acute, base with undifferentiated margin but transversely thickened at the widest point adaxially, puberulent except for glabrous base adaxially, puberulent on apex and medial portion of base but otherwise glabrous abaxially. Stamens 70-200; fertile stamens 1.0-1.2 mm long, narrowly oblong, apex of connective purplish red in vivo, 0.1-0.3 mm long, truncate to capitate, overhanging anther thecae, glabrous or minutely papillate, anthers 12-18-locellate, filament 0.2-0.3 mm long; outer staminodes 1.0-1.2 mm long, clavate to oblong, apex acute, obtuse, or truncate; inner staminodes 0.8-0.9 mm long, oblong, apex obtuse, rounded, or truncate; staminal cone 1.4-1.6 mm in diameter, 0.9-1.2 mm high, concealing only the bases of the ovaries, rim laciniate. Carpels 6 -11; ovaries ca. 1 mm long, narrowly oblong, sericeous, stigmas connivent, ca. 2.3 mm long, trowel-shaped, bearing a tuft of hairs at the apex. Torus flat, 1.5-1.8 mm in diameter. Fruit of up to 4 glabrate monocarps borne on a pedicel 4.2-5.3 mm long, 1.2-1.6 mm thick, sometimes with bracts persistent, pubescent; torus of fruit 1.9-2.3 mm in diameter, 0.9-1.8 mm high, depressed-globose. Monocarps with light green exterior and scarlet endocarp in vivo, 1.3-2.5 cm long, 0.5-1.2 cm wide, ca. 0.5-0.7 cm thick, oblong, weakly torulose, apex rounded with an oblique blunt beak 1-2 mm long, base contracted into a stipe 3-5 mm long, 1.5-2.1 mm thick, smooth or occasionally somewhat verrucose; pericarp ca. 0.2 mm thick. Seeds 1-3 per monocarp, in a single row, lying oblique to long axis, 9.2-9.8 mm long, 5.3-5.8 mm wide, 4.5-6.3 mm thick, pyriform, narrowed toward micropyle into a cylindrical neck 2.3-2.8 mm long and 2.8-3.6 mm wide, broadly elliptic in cross-section, obliquely truncate at micropylar end, rounded at chalazal end, brown, smooth, shiny, raphe/antiraphe not evident, micropylar scar 1.2-1.6 mm long, 0.8-1.0 mm wide, elliptic; sarcotesta bright orange, fleshy in vivo; aril absent.


Specimens with flowers have been collected in February, May to September, November, and December, and with fruits in February, March, June, July, and November.


(Fig. 22 View Figure 22 ). Occurs along the East African coast, from central Kenya south to central Tanzania, growing in forests and bushland, sometimes in secondary vegetation and usually on sandy soil, at elevations of 30-500 m.

Local names.

Mkabui (Holtz 321), mtuma-mrihi (Girama, Trump 96), mukunambawa (Girama, Langridge 58, Moggridge 389).

Additional specimens examined.

KENYA. Kilifi: Sokoke Forest, road to Jilore Forest Station, 3.2 km from turnoff on Kilifi-Malindi Road , Faden 71/696 (EA); Sokoke Forest , ca. 3 km on track S of Gede to Jilore Forest Station , ca. 3°18'S, 39°57'E, Faden & Faden 74/1225 (EA, K, MO, WAG); Sokoke Forest , Gisau 10 (EA, K), Langridge 58 (EA); K7, Mangea Hill summit, 03°15'S, 39°43'E, 500 m, 8 Apr 1987 (st), Luke & Robertson 318 (EA); K7, Mangea Hill, 3942E0316S, 480 m, 18 Feb 1988 (buds), Luke & Robertson 1008 (EA); 20.2 km Gotani to Bamba, 3°37'S, 39°32'E, 21 Nov 1989 (fl), Luke & Robertson 2134 (EA, K) GoogleMaps ; Kilifi, 17 May 1937 (fl), Moggridge 389 (EA, K); Arabuko-Sokoke Forest, N of Sokoke Forest Station, 3°25'- 3°30'S, 39°50- 39°54'E, 8 Jun 1973 (fl), Musyoki & Hansen 1007 (EA, K); forest 8 mi S of Jilore Forest Station, near road to Mida, 3°12'S, 39°55'E, Perdue & Kibuwa 10046 (EA, FI-T, K); Arabuko Sokoke Forest , 3°17'S, 39°56'E, 26 Dec 1983 (fl), Robertson 3727 (EA, K, MO); 4.5 km from Bamba toward Ganze, 3°33'S, 39°34'E, Robertson & Luke 6063 (EA); Mangea Hill summit, 3°15'S, 39°43'E, Robertson & Brummitt 6752 (K); Jilore-Mida, SW of Malindi, 3°19'S, 39°58'E, 18 Mar 1973 (st), Sangai EA 15703 (EA); Sokoke Forest GoogleMaps , Kilifi, Coast Province , 26 Mar 1954 (fr), Trump 96 (EA, K) .- Kwale: Mrima Hill, 7 Dec 1975 (fl), Kokwaro 3951 (K); Buda Mafisini F. R., 04°27'S, 39°24'E, 70 m, 23 Feb 1989 (st), Luke & Robertson 1686 (EA, K); Maluganji Forest Reserve (including Kaya Mtae), 04°06'S, 39°27'E, 200-300 m, 14 Nov 1989 (fl), Robertson & Luke 6000 (EA) GoogleMaps . TANZANIA. Pwani: Pugu Hills Forest Reserve, Kisarawe , 23 Aug 1972 (fl), Harris et al. DSM 2606 (MO) ; Dar es Salaam airport, 13 Sep 1970 (fl), Harris & Harris 4989 (B, MO); Pugu Hills near Kisarawe, 6°52-53'S, 39°04-06'E, 2 Nov 1970 (st), Harris & Schlieben BJH 5346 (DSM, EA, WAG); Pugu F. R., near Kisarawe, 31 Jul 1971 (fl), Harris et al. 5859 (MO); Kisarawe District , Pugu Hills Forest Reserve , Harris BJH 6771 (DSM), Harris & Siddiqi BJH 6749 (DSM); Pugu Forest Reserve , Hawthorne 1750 (K-2 sheets) ; Dar es Salaam Station, Sachsenwald , 30 Nov 1901 (fl bud, fr), Holtz 321 (EA) ; Dar es Salaam, 6 Dec 1901 (fl), Holtz 393 (EA, PRE); Kisarawe District, Pugu Forest Reserve , bus roundabout area ca. 4 km E of Kisarawe, 6°53'30"S, 39°06'E, 27 Feb 1996 (fl, fr), Johnson 1890 (DSM, OWU), 26 May 1996 (fl), Johnson & Murray 1937 (DSM, OWU); Pugu Forest Reserve , 6°54'18"S, 39°04'59"E, 270 m, 20 Aug 2003 (st), Kibure et al. 1019 (MO); Kisarawe District , Pugu Forest Reserve , 23 Aug 1972 (fl), Mabberley & Harris 1516 (K, WAG); Pugu Forest Reserve , E part of forest between Minaki Secondary School and Pugu Kajiungeno, 06°53'39"S, 39°06'00"E, 180 m, 2 Jun 2012 (fl), Mwangoka & Mulungu 7959 (MO); Kisarawe District , Kisarawe Forest Reserve , Paulo 118 (EA, K); Kisarawe District , Mogo Forest Reserve , Aug 1953 (fl), Semsei 51285 (EA) GoogleMaps .

This narrowly distributed species has distinctive long hairs on the twigs and leaves, ovate to lanceolate leaves that are acute at the apex, and usually solitary flowers with blunt buds. It shares with X. collina , X. keniensis , and X. tomentosa the characteristic of the tips of the inner petals bending sharply outward at anthesis, such that they emerge through the gaps between the erect outer petals. Description of the floral scent is varied, from over-ripe bananas to "smell of ' Annonaceae ' with overlying smell of cats" (Mabberley & Harris 1516).

A specimen from Tanzania, Abeid et al. 892 (MO), Pwani, Rufiji District, Kichi Hill Forest Reserve , NW of Nawanje village , Miselu / Mkinga Peak , 8°12'55"S, 38°38'55"E, 594 m, 27 Apr 2001 (fl), has peeling twigs and leaves similar in shape to those of X. arenaria , but the flowers were said to be purple, the outer petals are 4 mm wide at the base, and the specimen was taken from a tree 9 m tall growing at an elevation of 600 m. Fieldwork is needed to determine whether this plant is simply an aberrant specimen of X. arenaria or represents a distinct species GoogleMaps .

Despite being locally common in the Sokoke Forest area of Kenya and the Pugu Hills of Tanzania, Xylopia arenaria has yet to be collected from any area in between these two localities. The species grows in Brachystegia spiciformis woodland, and in lowland evergreen forests dominated by other ectomycorrhizal caesalpinioid legumes such as species of Afzelia , Cynometra , Julbernardia , Paramacrolobium , Erythrophloeum , and Hymenaea .

Other type material of the name Xylopia arenaria was not located, and the B sheet of Engler 2173, with good correspondence to the protologue, is formally designated here as a lectotype.