Page 2 - Morphoanatomical investigations of cones and pollen in Cathaya argyrophylla Chung & Kuang (Pinaceae, Coniferales) under systematical and evolutional aspects
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V. M. Dörken and H. Nimsch Feddes Repertorium 2014, 125, 25–38
1990; Sporne 1965). Currently limited data are available “sporophyll” or “microsporophyll” for the sporangia bear-
on the morphology and anatomy of Cathaya and espe- ing structure. Otherwise we would introduce a priory a
cially on its cones. Furthermore, the few available mor- homology with leaves.
phological data on the structure of pollen- and seed-
cones are often conflicting (see Callaghan 2011). A very
detailed study on morphology and anatomy of the vege- 3 Results
tative organs was published by Hu & Wang (1984).
Since 2012 an individual cultivated in the living collection 3.1 Morphology and anatomy of seed-cones
of Hubertus Nimsch, Bollschweil, St. Ulrich (Germany)
has developed several pollen- and seed-cones. This was Seed-cones are developed in distal parts of the crown.
taken as an opportunity to investigate the cone- Here they are arranged in distal parts of ascending
morphology and cone-anatomy in detail. Anatomical shoots, where several cones (4–10) are formed close to
data about the seed-scale can be taken from the very each other (Fig. 1A). The shoot axis and the lateral
detailed study published by Hu et al. (1989). Thus, in the seed-cones are developed sylleptically from the same
present study, only additional data to Hu et al. (1989) are terminal hibernating bud. Each seed-cone is inserted in
presented. the axil of a typical needle-like trophophyll (Fig. 1B). Bud
scales surrounding the seed-cones are absent. At polli-
nation in May seed-cones are erect (Fig. 1B) and be-
2 Material and methods tween 4.2–5.1 mm long and 3.8–4.7 mm wide. The stalk
of the cone is between 3.5–5.6 mm long and 2.5–
2.1 Material 3.1 mm in diameter. Several small needle-leaves, sig-
nificantly smaller than typical trophophylls, are inserted
Seed- and pollen-cones were collected in the living col- on the stalk and overtop the distal receptive seed-cone
lection of Hubertus Nimsch, Bollschweil, St. Ulrich (Ger- at pollination (Fig. 1C). In ripe seed-cones these leaves
many) from a 2.5 m high and 14-years-old individual. can still be found at the stalk below the cone-scales
This individual was grown from seed. It is cultivated as a (Fig. 1E). There are no intermediates between needle-
potted plant and overwintered in a temperate house. leaves and cone-scales. The seed-cone consists of
Pollen- and seed-cones were collected on 05.05.2014. 12–16 cone-scale/seed-scale complexes (Fig. 1D). Only
Seed-cones were continuously collected at two week the cone-scales in the middle of the cone are fertile.
intervals untill September. Ovules are absent on the most basal and most distal
ones. At pollination the cone-scales are 3–4 mm long
2.2 Methods (Figs. 1D, 2A, B) and significantly larger than the ovu-
liferous seed-scales (1–1.5 mm) (Fig. 3E). At pollination
Freshly collected material was photographed and then only the cone-scales, whose tips are strictly curved up-
fixed in FAA (100 ml FAA = 90 ml 70% ethanol + 5 ml wards, are visible externally (Figs. 1D, 3D). The seed-
acetic acid 96% + 5 ml formaldehyde solution 37%) scales are deeply hidden within the cone. The cone-
before being stored in 70% ethanol. The cone-anatomy scales in receptive cones are bright red with greenish
was studied from serial sections using the classical bases (Fig. 1D), while the seed-scales are pale green. At
paraffin technique and subsequent astrablue/safranin the margin of the basal half of the cone-scales several
staining (Gerlach 1984). For SEM-analysis the FAA- glandular hairs are developed (Fig. 2B, C). The base
material was dehydrated in formaldehyde dimethyl of the cone-/seed-scale complex is slightly narrowed,
acetal (FDA) for at least 24 hours (Gerstberger & Leins however, not pedicellate (Fig. 2A, B). Cone- and seed-
1978) and critical point dried. Sputter coating was done scales are congenitally fused in the basal part. Each
with a sputter coater SCD 50 Bal-tec (Balzers). The scale is supplied by its own bundle strand (Fig. 3E). The
specimens were examined with an Auriga Zeiss TM. vascular bundles enter the cone axis as separate
Macrophotography was accomplished using a digital strands.
camera (Canon PowerShot IS2) and microphotography At pollination time the cone is widely open and all
with a digital microscope (Keyence VHX 500F) equipped cone-scales are distant from each other (Fig. 1D). After
with a high-precision VH mounting stand with X–Y stage successful pollination the cones close first by an elonga-
and bright field illumination (Keyence VH-S5). tion of the cone-scales and later by the rapidly develop-
ing seed-scales. One week after pollination the cone-
2.3 Special terms scales are 5–7 mm long, the seed-scales 4–6 mm. The
maturing seed-scales are greyish-green. The ripe seed-
Most authors regard the coniferous microsporangiopho- scales are brownish, strongly lignified and woody, be-
res as microsporophylls. We avoid using the term tween 1.4–2.3 cm long, and overtop the cone-scales,
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