Evolutionary Biology

Alasemenia, the earliest ovule with three wings and without cupule

Deming Wang author has email address
Jiangnan Yang
Le Liu
Yi Zhou
Peng Xu
Min Qin author has email address
Pu Huang

Key Laboratory of Orogenic Belts and Crustal Evolution, Department of Geology, Peking University, Beijing, China
School of Geoscience and Surveying Engineering, China University of Mining and Technology (Beijing), Beijing, China
School of Life Sciences, Sun Yat-Sen University, Guangzhou, China
College of Life Sciences, Linyi University, Linyi, China
Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing, China

https://doi.org/10.7554/eLife.92962.2

Open access
Copyright information

Figures and data

Fertile branches and seeds of Alasemenia tria gen. et sp. nov.
a, Thrice dichotomous branch with a terminal ovule. Arrow indicating boundary between ovule and ultimate axis (PKUB21721a). b, f, g, i, Once dichotomous branch with a terminal ovule (PKUB21781, PKUB23132, PKUB19338a, PKUB17899). c, Twice dichotomous branch with a terminal ovule (PKUB19713a). d, e, Ovule with three integumentary wings (PKUB19321, PKUB19316). h, Ovule showing two integumentary wings (PKUB19282). j, k, Ovule terminating short ultimate axis (PKUB23114, PKUB23129). Scale bars, 1 cm (a-c, h), 5 mm (d-g, i-k).

Fertile branches and seeds of Alasemenia tria gen. et sp. nov.
a-c, Once dichotomous branch with a terminal ovule. a, b, Part and counterpart (PKUB16876a, b, PKUB17767). d, e, Part and counterpart, arrow showing the third integumentary wing (PKUB19322a, b). f, Ovule on ultimate axis (PKUB21752). g, h, k-m, Ovules lacking ultimate axis (PKUB16788, PKUB21631, PKUB16522 PKUB21647, PKUB21656). i, j, Part and counterpart, showing limit (arrows) between nucellus and integument (PKUB19339a, b). n, Four detached ovules (arrows 1-4) (PKUB19331). o, Enlarged ovule in n (arrow 2), showing three integumentary wings (arrows). Scale bars, 1 cm (n), 5 mm (a-h, k-m, o), 2 mm (i, j).

Seeds of Alasemenia tria gen. et sp. nov.
a, b, Part and counterpart, enlarged ovule in Fig. 1a (PKUB21721a, b). c, Enlarged ovule in Fig. 1c. d, Counterpart of ovule in c (PKUB19713b). e, Dégagement of ovule in d, exposing the base of the third integumentary wing (arrow). f, Enlarged ovule in Fig. 1d. g, h, Enlarged ovule in Fig. 2i, j, respectively. Scale bars, 5 mm (a-e), 2 mm (f-h).

Transverse sections of seeds of Alasemenia tria gen. et sp. nov.
a, b, Part and counterpart. c-e, Sections of seed in a and b (at three lines, in ascending orders). Arrow in d indicating probable nucellar tip (Slide PKUBC17913-12b, 10a, 9b). f, g, Part and counterpart. h-k, Sections of seed in f and g (at four lines, in ascending orders) (Slide PKUBC19798-8b, 6b, 4a, 4b). l, m, Part and counterpart. n-r, Sections of seed in l and m (at five lines, in ascending orders), showing three wings departing centrifugally (Slide PKUBC17835-5a, 7b, 8b, 9a, 10a). s, v, A, One seed sectioned. t, u, Sections of seed in s (at two lines, in ascending orders) (Slide PKUBC18716-8b, 7a). w-z, Sections of seed in v (at four lines, in ascending orders) (Slide PKUBC20774-7a, 6b, 3a, 3b). B-E, Sections of seed in A (at four lines, in ascending orders), showing three wings departing centrifugally (Slide PKUB17904-5b, 4a, 4b, 3b). Scale bars, 2 mm (a, b, f, g, l, m, s, v, A), 1 mm (c-e, h-k, n-r, t, u, w-z, B-E).

Reconstruction of two acupulate ovules with integumentary wings.
a, Alasemenia tria with three wings distally extending outwards. b, A. tria with one of three wings partly removed to show nucellar tip. c, Guazia dongzhiensis with four wings distally extending inwards (Wang et al., 2022). Scale bars, 5 mm.

The mathematical analysis of wind dispersal ability of ovules with 1-4 wings.
The maximum windward area of each wing is S_wing and n represents the number of wings per ovule. r is the distance from the tip of wing to the axis of ovules. S(θ) represents the area of windward when the angle between airflow and wings is θ, and D(θ) represents the accumulated area of windward in a cycle. E_r(%) means relative efficiency for wind dispersal. Red lines and expressions show the situation of n = 1.

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