Alseodaphnopsis

van der Werff, H., 2019, Alseodaphnopsis (Lauraceae) revisited, Blumea 64 (2), pp. 186-189 : 187-189

Flowers of Alseodaphnopsis

All genera of the Persea group share a common flower structure. The flowers have two whorls of three tepals each; in most cases the six tepals are equal, but occasionally unequal with the outer three shorter than the inner three. Stamens are ar- ranged in three whorls of three stamens each; stamens of the third whorl have each two glands at the base of the filaments. A fourth, innermost whorl is usually present and staminodial, but may be lacking entirely. The pistil is superior.

Alseodaphnopsis andersonii (King ex Hook.f.) H.W.Li & J.Li is a relatively common species of which several flowering collections are known. As part of a search for reproductive characters diagnostic for Alseodaphnopsis these flowering specimens were studied and two flower types were found to be present. One flower type has a large pistil and small stamens, the stamens shorter that the pistil and with anthers that show four locelli that do not open ( Fig. 1a ). The second type has a small pistil, shorter than the stamens and large stamens with open locelli ( Fig. 1b ). These different flower types can be explained in two ways. It could be that the flowers are unisexual and the species dioecious. But dioecy has never been reported for any member of the Persea group. In Asia, unisexual flowers in Lauraceae are only known in the Litsea group, a group of genera with flowers in umbels or pseudo-umbels. It is also possible that the two flower types are an example of dichogamy, a system in which the flowers pass through separate pistillate and staminate phases. During the pistillate phase the stamens are relatively undeveloped and the locelli remain closed, while the pistil is functional with a receptive stigma. During the following staminate phase the stamens develop further, the locelli open and shed pollen, while the stigma dries out and the pistil cannot be fertilized. Dichogamy was first demonstrated in the cultivated Persea americana Mill. ( Stout 1927). Kubitzki & Kurz (1984) reported dichogamy for Lauraceae in Amazonian Brazil and I have observed dichogamy in species of Licaria Aubl. and Cryptocarya . Dichogamy thus appears to be a common flowering process among Lauraceae with bisexual flowers. Whether flowers are unisexual or bisexual with dichogamy can be determined most easily by examining the base of young fruits with remnants of floral parts. In the case of unisexual flowers, staminodes can be expected among floral remnants on young fruits; in the case of bisexual flowers stamens with opened locelli can be expected. In the case of Alseodaphnopsis andersonii staminodes were found at the base of young fruits ( Fig. 1c ). For comparison, Fig. 1d shows a stamen of A. andersonii . This confirms that the flowers of Alseodaphnopsis andersonii are unisexual. This is the first time that unisexual flowers have been found on any species of the Persea group. Alseodaphnopsis lanuginosa (Kosterm.) H.W.Li & J.Li was also found to have two flower types, similar to Alseodaphnopsis andersonii (pistillate flowers: Pételot 3386bis, MO; staminate flowers: Pételot 3565, MO). A single flowering collection of Alseodaphnopsis petiolaris (Meisn.) H.W.Li & J.Li ( Fig. 1e ) was found to have staminate flowers and an unidentified collection from Thailand ( Maxwell 07-702, MO) has pistillate flowers. Because the type species of Alseodaphnopsis , A. petiolaris , was found to have unisexual flowers, I propose to accept as diagnostic character for Alseodaphnopsis the presence of unisexual flowers instead of the characters proposed by Mo et al. (2017). I would further accept in Alseodaphnopsis A. andersonii , A. lanuginosa and the unidentified species represented by Maxwell 07-702. These four species form a homogeneous group characterized by large, chartaceous leaves (mostly 20–30 cm long) and large inflorescences ( 20–30 cm long; Maxwell 07-702 has inflorescences to 15 cm long). Two other species placed in Alseodaphnopsis by Mo et al. (2017), A. hainanensis (Merr.) H.W.Li & J.Li and A. rugosa (Merr. & Chun) H.W.Li & J.Li , appear quite different in their thick, coriaceous, narrowly elliptic to narrowly obovate leaves to 10 cm long. I have not seen flowers of these species. Their relationship is probably with Alseodaphne rhododendropsis Kosterm. , a species from Central Vietnam. The other species placed by Mo et al. (2017) in Alseodaphnopsis are not known to me. Alseodaphnopsis petiolaris , A. andersonii and A. lanuginosa resemble each other closely and have been confused. Two collections of Alseodaphnopsis lanuginosa, Pételot 3386 and 3386bis (both at MO) were annotated by Kostermans as Alseodaphne andersonii and cited as such in the synopsis of Alseodaphne ( Kostermans 1973) ; duplicates of Pételot 3565 in L and MO, the type of A. lanuginosa , have labels copied by Kostermans from the original label of the holotype in P and give as altitude 400 m instead of 1 500 m on the holotype; three collections of A. andersonii in P ( Poilane 20964, 30298 and 15704) were initially identified as A. petiolaris ; Poilane 18974 (L) was identified and cited in Kostermans (1973), as A. lanuginosa , but appears to be A. andersonii .

Alseodaphne , Dehaasia and Nothaphoebe have never been revised. A better understanding of the species is necessary for a better understanding of the generic boundaries. Because the current concepts of the genera are based on flower characters – Alseodaphne with bisexual flowers, equal tepals and 4-locular stamens, Alseodaphnopsis with unisexual flowers, Dehaasia with 2-locular stamens, and Nothaphoebe with bisexual flowers, unequal tepals and 4-locular stamens –, revisions should be based on flowering specimens. As Kochummen (1989) already commented, describing new species in Alseodaphne or Dehaasia based on fruiting specimens alone is unwise. Once the four genera mentioned above have been revised, it will become possible to determine if those genera are monophyletic.

Figures

Fig. 1 a–d. Alseodaphnopsis andersonii (King ex Hook.f.) H.W.Li & J.Li. a. Pistillate flower. Several tepals removed. Note the large pistil and staminodes with rudimentary locelli; b. staminate flower. Two tepals removed. Note the slender, short pistillode and large stamens with opened locelli; c. staminode taken from the base of a young fruit; d. anther with small part of the filament. Note the large locelli, two with flaps still attached, two without the flaps. – e. Alseodaphnopsis petiolaris (Meisn.) H.W.Li & J.Li. Staminate flower. Several tepals removed. Note three of the outer six stamens and two stamens of the inner whorl. A pistillode is lacking. The three low bodies in the foreground are glands present at the base of the inner stamens (a. Hyland 14931, MO; b, d. Poilane 30298, P; c. Van der Werff 23885, MO; e. Jitlan 12, L).