Alseis includes perhaps 20 Neotropical species of shrubs and small to quite large trees. Alseis is distinctive morphologically with some unusual characters in Rubiaceae, but it is difficult to recognize in a sterile condition and flowering specimens are difficult to match to fruiting specimens so species can be difficult to identity. Alseis is characterized by its woody, often large, deciduous habit; medium-sized, elliptic to obovate leaves that sometimes have pubescent domatia; triangular caducous stipules that are twisted in bud; racemiform to spiciform, usually multiflowered inflorescences that are mostly axillary and grouped at the ends of the stems; rather small 5-merous flowers that are protogynous with staminate and pistilllate phases that differ markedly in size and form; white to pale green corollas with the lobes relatively short and imbricated to open in bud; and rather small, generally clavate, woody capsules with septicidal dehiscence and numerous fusiform seeds that are flattened and winged. Alseis species are characteristically deciduous, even when growing in wet habitats, and the flowers are generally produced along with the flush of new leaves. The stems are often notably lenticellate. The stipules are imbricated in bud, and then the stipule group is longitudinally twisted; their size, shape, and arrangement are rather distinctive and help recognize Alseis, but the stipules are caducous and often not present. The leaves are generally shortly petiolate and obovate.  Some leaves in some species have spreading hisute pubescence along the costa that may function as domatia (e.g., Alseis microcarpa, Alseis smithii). This genus is widespread, from Mexico to Bolivia and southern Brazil. Alseis usually has only one or a few species in most regions, and these often seem to grow in different habitats within the region (e.g., Marinho & Jardim, 2016). Its center of species diversity is in eastern and southeastern Brazil. Most of the species seem to have rather broad ranges but a few are endemic to particular areas with distinctive ecological formations (e.g., Alseis costaricensis, Alseis eggersii, Alseis involuta). Various species are frequently collected in their ranges but no particular Alseis species seems to be markedly more common than others. 

Alseis has a several distinctive features. Several of its species are canopy trees in tall forest; such large trees are not common in Rubiaceae. Its branching is usually sylleptic as well as evidently seasonal, with the lateral branch originating from the axil of a lower node and producing one or two elongated internodes and then several short, closely-set nodes with leaves and inflorescences. At least some species of Alseis also have milky sap, which is uncommon in Rubiaceae (Alseis blackiana, Alseis reticulata). The bark is generally reported to be fibrous and rather smooth to ruguse. The stipules often are hardened and at least at times function as bud scales for dormant growth. The axillary inflorescences are generally elongated and grouped with the leaves on the apical part of the stem, and sometimes a terminal inflorescence is also produced; stem growth then continues from a lower node. The spiciform or racemiform inflorescences borne at each node are unbranched or sometimes branched to 1 order, but they are usually produced at several nodes and grouped together to appear paniculiform. A few Alseis species do have shortened,sometimes subcapitate inflorescences that are interpreted as reduced (e.g., Alseis involuta, Alseis sertaneja). The capsules are woody, and the valves often curve away from each other when they open and then persist on the inflorescence axis after the seeds have been released.  

The flowers of Alseis are unusual in being protogynous and  markedly dimorphic: the first, pistillate-phase flowers generally have quite a short cylindrical corolla that is still closed at the top with only the stigmas protruded, then the corolla enlarges up to twice or more its previous length and becomes funnelform with the anthers now developed and exserted, and the stigmas and style drying up then falling off. The inflorescences are indeterminate and characteristically have pistillate-phase flowers in the apical portion, staminate-phase flowers below them, and developing fruits below that. Protogynous flowers are unusual in angiosperms, and found in few Rubiaceae genera. The pistillate and staminate flowers of Alseis species are so distinct they have sometimes been mistaken for different genera in herbarium identifications. Alseis sertaneja was described in its protologue as having protogynous flowers, but also as being monoecious (Marinho & Jardim, 2016) but without details of unisexual flowers or any further comment about conflict between those two descriptions of the flowering biology. A bisexual flower entering the staminate phase is illustrated there (Marinho & Jardim, 2016: fig. 1D), and agrees with the form of the bisexual flowers of other Alseis species. It is unclear if these flowers are monoecious functionally, or if the description of monoecy may have been a misinterpretation of the protogyny found in this genus or was intended to describe the phenology of the individual flowers as temporally monoecious.

The species taxonomy of Alseis has not been studied comprehensively, and is provisional for many regions. The species of Alseis are not well documented as to their characteristics, and are not easy to identify or understand due to the difficulty of finding reproductive material due to the usually large size of the plants at flowering (20-30 m) and the similarity of the flowers and fruits of various species. Species are often separated largely by vegetative characters, which are problematic to evaluate due to the usually complete seasonal separation of the flowers from the leaves and fruits, which makes conclusive matching of the the reproductive stages of single species difficult. In fact, the flowers of some species are not well knonw. Alseis was studied taxonomically in eastern Brazil by Pereira-Moura & Giulietti (2001), who presented a useful but still-unpublished revision. Otherwise, this genus has been studied only floristically for several regions (e.g., Andersson & Taylor, 1994; Taylor, 2002; Lorence et al. 2012; Steyermark, 1974; Steyermark et al., 2004). The species are separated here largely based on geographic range and habitat. Molecular data are likely to be particularly helpful for our understanding of species diversification in Alseis. 

The systematic relationships of Alseis have been unclear, along with some other genera. It was considered related to Cinchona for some time, but Andersson & Persson (1994) separated it in Calycophylleae based on morphological analysis, and later  Kainulainen et al. (2010; as Condamineeae) clarified with molecular sequence data that these genera belong to the Tribe Dialypetalantheae. Kainulainen et al. found it placed in their "Septicidal Clade" and related to Calycophyllum, Dialypetalanthus, Bothriospora, and Wittmackanthus. 

Alseis is generally distinctive in fruit but can be difficult to recognize at other stages. The flowers are generally accompanied only by very young, just-flushing leaves and their protogynous form is odd. Flowering plants are sometimes confused with genera of other families, such as Terminalia. Sterile Alseis plants are frequently collected in tree plot inventories, and left unidentified as to genus or confused with Chimarrhis, which usually has longer stipules that are often nire twisted in bud, e.g., to 360° or more. Alseis is also sometimes confused with Warszewiczia, which also has twisted stipules, spiciform inflorescence axes, protogynous flowers, and capsular fruits; Warszewiczia can be separated by its subglobose to ellipsoid, septicidal capsules . 

Author: C.M. Taylor
The content of this web page is under construction, and was last revised on 8 December 2022.
Taylor web page: http://www.mobot.org/MOBOT/Research/curators/taylor.shtml

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