Bryophyllum, Salisbury, 1805

Smith, Gideon F., 2022, Notes on Kalanchoe subg. Bryophyllum (Crassulaceae subfam. Kalanchooideae) and the kalanchoes of Sijfert H. Koorders (1919), Phytotaxa 549 (1), pp. 87-96 : 88-89

Bryophyllum recognised as a subgenus in Kalanchoe by Koorders (1919)

Koorders (1919: 169–170) stated: “Eine vergleichende Untersuchung der 2 bisher von Java bekannten Crassulaceae-Gattungen Kalanchoë und Bryophyllum hat mich zu der Ueberzeugung geführt, dass es Empfehlung verdient Bryophyllum als Gattung einzuziehen und mit Kalanchoë zu vereinigen. Ein durchgreifender Unterschied zwischen diesen beiden Gattungen giebt es, soweit ich feststellen konnte, nicht, weil einige (ausserhalb Java vorkommende) Kalanchoë - Arten bekannt sind, welche Kelchblätter besitzen, die bis zur Mitte mit einander verwachsen sind und dadurch einen natürlichen Uebergang bilden zu der Gattung Bryophyllum , die sich nur durch einen bauchigkurzzipfeligen Kelch nur unbedeutend von Kalanchoë (im engeren Sinne) unterscheidet.” [English: “A comparative investigation of the two Crassulaceae genera hitherto known from Java, Kalanchoe and Bryophyllum , has led me to the conviction that it deserves recommendation to combine the genus Bryophyllum with Kalanchoe . As far as I could determine, there is no fundamental difference between these two genera, because some Kalanchoe species (occurring outside Java [an island in Indonesia]) are known that have sepals fused with each other up to the middle, and thereby form a natural transition to the genus Bryophyllum , which differs only insignificantly from Kalanchoe (sensu stricto) by a bulbous, short-lobed calyx.”]

Koorders (1919: 170) then formally includes Bryophyllum in Kalanchoe when he states “Mit Einschluss von Bryophyllum [in Kalanchoe ]”, and in the key to the species of the entire island [“Arten der Gesamtinsel”] gives the rank of Bryophyllum , under Kalanchoe , as “Untergattung”, i.e., subgenus. This is regarded as Koorders (1919: 170) having provided indirect reference to Salisbury (1805: t. 3), where the genus name Bryophyllum was published (see Turland et al. 2018: Art. 41.4).

Koorders (1919: 170) additionally recognised the subgenus ‘ K. subg. Eukalanchoe ’, nom. inval., i.e., K. subg. Kalanchoe . However, epithets for subdivisions of a genus may not consist of the name of the genus with the prefix “ Eu -” and a subdivision of a genus that includes the type of the genus must repeat the name of the genus unaltered ( Turland et al. 2018: Art. 21.3 and Ex. 3, and Articles 22.1 and 22.2).

When treated as a subgenus of Kalanchoe , the nomenclature of Bryophyllum , i.e., as K. subg. Bryophyllum , resolves as follows:

Kalanchoe Adanson (1763: 248) subg. Bryophyllum (Salisb.) Koorders (1919: 170) . Basionym:— Bryophyllum Salisbury (1805 : t. 3). Homotypic synonym:— Kalanchoe sect. Bryophyllum (Salisb.) Boiteau (1947: 7) , pro parte, excluding K. porphyrocalyx (Baker 1883: 142) Baillon (1885: 469) (Smith & Shtein 2021: 234–235). Type:— Bryophyllum calycinum Salisbury (1805 : t. 3), currently accepted name Kalanchoe pinnata ( Lamarck 1786: 141) Persoon (1805: 446) . See Wickens (1987: 27), Farr & Zijlstra (1996+), Smith & Figueiredo (2018a: 169), and Smith & Figueiredo (2018b: 222).

Nomenclatural notes:—Note that Wickens (1987: 27) included Physocalycium Vest (1820: 409) , nom. illeg. ( Turland et al. 2018: Art. 52.1) in the synonymy of Bryophyllum . However, Physocalycium , with Vereia crenata Andrews (1798: t. 21), a synonym of the African K. crenata (Andrews) Haworth (1812: 109) , the only element having been included, is representative of K. subg. Kalanchoe . Physocalycium therefore does not belong in the synonymy of Bryophyllum , or in that of K. subg. Bryophyllum , for that matter.

Some species better accommodated in K. subg. Bryophyllum were previously included in Kitchingia , pro parte, excluding type, and in Kalanchoe sect. Kitchingia (Baker) Boiteau (1947: 7) , pro parte, excluding type. The lectotype of Kitchingia is Kitchingia gracilipes Baker (1881: 268) , which was designated by Smith & Figueiredo (2018a: 169); its currently accepted name is Kalanchoe gracilipes (Baker) Baillon (1885: 469) .

Diagnosis:—Species and infraspecific taxa included in K. subg. Bryophyllum , and nothospecies derived from intra-subgenus hybridisation generally have a perennial, biennial, or short-lived multiannual lifespan, with plants being terrestrial and ± herbaceous to brittle-woody. Representatives of K. subg. Bryophyllum differ from taxa included in other subgenera recognised in Kalanchoe by variously developing bulbils on the leaf blade margins, typically at the indentations between crenations or teeth, i.e., they are phyllo-bulbiliferous (not observed in the case of K. streptantha Baker (1887: 472) [see Smith & Figueiredo 2021: 199]); by having tetramerous flowers that are usually distinctly pendulous at anthesis; by the sepals usually being substantially fused into a conspicuous tube; a corolla tube that is often substantially obscured by the calyx tube, especially lower down at the level of the carpels; by having the corolla tube indented-constricted ± above the carpels so often giving it a bulbous appearance; by the filaments being ± inserted in the lower ⅓ of the corolla tube and often being adnate to the corolla very low down; by the anthers being ± exserted or at least distinctly visible at the mouth; by having four filaments of two similar lengths; by having the carpels shorter than the styles; and by having nectar scales that are generally wider than long. Several representatives of K. subg. Bryophyllum have developed multiple reproductive mechanisms and have a tendency to become naturalised and weedy in places well separated from their natural distribution ranges in Madagascar ( Smith et al. 2021c).