Angraecum humbertii

Angraecum humbertii H.Perrier is an accepted Madagascan orchid in the family Orchidaceae. Kew Plants of the World Online treats it as a lithophytic subshrub of seasonally dry tropical biome and gives its native range as SE Madagascar [1]. A horticultural habitat account in IOSPE instead places it in southwestern Madagascar, growing on rocks in dry deciduous forests on western mountain slopes at about 800 m [2]. The name is not in dispute in the supplied sources, but the regional distribution conflict should be kept visible rather than smoothed over.

Names and Taxonomy

Angraecum humbertii H.Perrier was first published in Notulae Systematicae (Paris) 8: 46 (1939), according to POWO [1]. POWO accepts the name and lists one homotypic synonym: Arachnangraecum humbertii (H.Perrier) Szlach., Mytnik & Grochocka, published in Biodiversity Research and Conservation 29: 11 (2013) [1]. Because the synonym is homotypic, it is based on the same type as A. humbertii; it should not be treated as a separate species in a species profile.

IOSPE gives the common name Humbert’s Angraecum and lists the species under section Arachnangraecum [2]. The POWO excerpt supplied here does not provide a sectional placement, so the section note is best treated as source-specific rather than as a full modern classification. No varieties or subspecies are documented in the supplied excerpts. The requested phrase “SW Madagascar” is a geographic qualifier, not part of the scientific name.

How to Identify This Species

The available species description is brief but diagnostic in habit. IOSPE describes A. humbertii as a small-sized, warm-growing lithophyte with a short, thick, slightly compressed stem [2]. The leaves are two-ranked, broadly linear to loriform, often conduplicate, leathery, slightly glossy, and very unequally bilobed at the apex, with rounded lobes and clasping bases [2]. The root system is not described in the supplied excerpts.

IOSPE reports a flower size of 5 in (12.5 cm) and a robust inflorescence about 8 in (20 cm) long, bearing four to eight successively flowered blooms, two to three acute sheaths, and a very thin floral bract [2]. Those measurements are from a single horticultural source and were not independently checked here. The supplied excerpts do not document flower color, lip shape, spur length, fragrance, or pollinator, so identification should not be based on a name label or a single photograph. A plant matching the leaf arrangement and reported flower dimensions is a candidate, but confirmation should rely on verified botanical material and, ideally, the original description or a flora treatment.

Native Range and Habitat

POWO gives the native range as SE Madagascar and describes the species as a lithophytic subshrub growing primarily in the seasonally dry tropical biome [1]. IOSPE separately reports southwestern Madagascar, with plants growing on rocks in dry deciduous forests on the western slopes of mountains, on rocky outcrops, at elevations around 800 m [2]. The CITES Orchid Checklist also lists the species for Madagascar [3], which supports the country-level distribution but does not resolve the regional disagreement.

The conflict between “SE Madagascar” in POWO and “southwestern Madagascar” in IOSPE is material and should not be averaged into a vague “southern Madagascar” statement. The two sources may reflect different data sets, different circumscriptions of regional terms, or a distribution that spans more than one area; the supplied excerpts do not allow a conclusion. The documented habitat is lithophytic, not epiphytic or terrestrial: plants are reported on rocks and rocky outcrops in dry deciduous forest [1][2]. No introduced or cultivated occurrence is treated here as part of the native range. Seasonality is indicated by the seasonally dry tropical biome and dry deciduous forest descriptors [1][2], but the excerpts do not give a month-by-month rainfall pattern or a microhabitat temperature record.

Species-Specific Care

Species-specific cultivation evidence is limited. The table below separates what is documented from what is absent; it does not convert habitat data into greenhouse setpoints.

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The most defensible care statement is therefore narrow: A. humbertii is documented as a warm-growing lithophyte, and its habitat is rocky and seasonally dry [1][2]. Growers should not assume that every Angraecum requires the same watering, humidity, or resting regime. Where no species-specific trial is available, any culture recommendation should be labeled as an inference and adjusted cautiously. The absence of a documented dry rest is especially important: the seasonally dry habitat does not by itself prove that cultivated plants should be kept dry for a fixed period.

Flowering and Pollination

IOSPE reports that A. humbertii blooms in late spring and early summer on a robust inflorescence about 20 cm long, with four to eight successively opening flowers [2]. The same source gives a flower size of 12.5 cm [2]. Because the excerpt does not state whether those months refer to the Southern or Northern Hemisphere, or to a particular greenhouse, the flowering period should be treated as source-specific rather than universal. “Successively flowered” indicates that the blooms open over a period rather than all at once, but the supplied excerpt does not give flower longevity.

No species-specific pollinator, nectar spur measurement, fragrance timing, or pollination mechanism is documented in the supplied sources. The genus Angraecum includes long-spurred species with specialized moth associations, but that general context must not be transferred to A. humbertii without evidence. For this profile, pollination is best recorded as not documented in the available sources.

Conservation and Responsible Cultivation

No formal conservation assessment for A. humbertii is documented in the supplied excerpts. The CITES Orchid Checklist lists the name and a Madagascar distribution [3], but that checklist is a nomenclatural reference, not a conservation status or a determination of legal trade status. Habitat loss and collection pressure are general concerns for Madagascan orchids, but the supplied sources do not quantify them for this species. Cultivation should be based on verified provenance; this profile makes no claim about the legality or sustainability of any particular nursery stock.

Evidence and Limitations

This profile relies on search snippets from POWO, IOSPE, and the CITES Orchid Checklist, not on full-page or full-paper verification [1][2][3]. The principal unresolved point is distribution: POWO says SE Madagascar, while IOSPE says southwestern Madagascar. The flower size, inflorescence length, flower count, and flowering months come from IOSPE and were not independently verified here. Root description, flower color, lip and spur morphology, fragrance, pollinator, flower longevity, and numerical cultivation thresholds are not documented in the supplied evidence. No formal conservation assessment was supplied. Identification of cultivated plants should be checked against verified botanical descriptions and photographs with known identity and rights; no image is requested or supplied in this profile.