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{{rh|{{x-larger|538 }}|{{x-larger|PALAEOBOTANY}}|[PALAEOZOIC}} |
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in reality very distinct. Both male and female inflorescences |
in reality very distinct. Both male and female inflorescences |
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have frequently been found in connexion with leaf-bearing branches |
have frequently been found in connexion with leaf-bearing branches |
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(see restoration, fig. |
(see restoration, fig. 30). The inflorescence is usually a spike |
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bearing lateral cones or catkins, arranged sometimes distichously, |
bearing lateral cones or catkins, arranged sometimes distichously, |
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sometimes in a spiral order. The investigation of silicified |
sometimes in a spiral order. The investigation of silicified |
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specimens has, in the hands of Renault, yielded striking results. |
specimens has, in the hands of Renault, yielded striking results. |
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A longitudinal section of a male ''Cordaianthus'' (the name applied to |
A longitudinal section of a male ''Cordaianthus'' (the name applied to |
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isolated fructifications) is shown in fig. |
isolated fructifications) is shown in fig. 31, A, Plate. The organ |
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figured is one of the catkins (about a centimetre in length) which |
figured is one of the catkins (about a centimetre in length) which |
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were borne laterally on the spike. Some of the stamens are inserted |
were borne laterally on the spike. Some of the stamens are inserted |
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are grouped about the apex of the axis. Each stamen consists |
are grouped about the apex of the axis. Each stamen consists |
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of a long filament, bearing several erect, cylindrical pollen-sacs at |
of a long filament, bearing several erect, cylindrical pollen-sacs at |
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its summit (cf. fig. |
its summit (cf. fig. 31, B, Plate). Some of the pollen-sacs had |
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dehisced, while others still retained their pollen. The stamens are |
dehisced, while others still retained their pollen. The stamens are |
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probably best compared with those of ''Ginkgo'', but they have also |
probably best compared with those of ''Ginkgo'', but they have also |
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ovules, each accompanied by a few bracts, while in others the lateral |
ovules, each accompanied by a few bracts, while in others the lateral |
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appendages are catkins, each containing from two to several ovules. |
appendages are catkins, each containing from two to several ovules. |
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In the catkin shown in longitudinal section in fig. |
In the catkin shown in longitudinal section in fig. 32, A, it appears |
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that each ovule was borne terminally, on an extremely short axillary |
that each ovule was borne terminally, on an extremely short axillary |
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shoot, as in ''Taxus'' among recent Gymnosperms. The ovule consists |
shoot, as in ''Taxus'' among recent Gymnosperms. The ovule consists |
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or pollen-chamber, with a narrow canal leading into it, precisely |
or pollen-chamber, with a narrow canal leading into it, precisely |
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as in the ovules of ''Stangeria'' or other Cycads at the present day |
as in the ovules of ''Stangeria'' or other Cycads at the present day |
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(fig. |
(fig. 32, B). Within the pollen-chamber, and in the canal, pollen-grains |
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are found, agreeing with those in the anthers, but usually |
are found, agreeing with those in the anthers, but usually |
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of larger size (fig. |
of larger size (fig. 32, C). It was in this case that Renault first |
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<!-- column 2 --> |
<!-- column 2 --> |
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made the exceedingly interesting discovery that each pollen-grain |
made the exceedingly interesting discovery that each pollen-grain |
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contains a group of cells, presumably representing an antheridium |
contains a group of cells, presumably representing an antheridium |
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(fig. |
(fig. 32, C). Recent observations have completely confirmed |
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Renault’s interpretation of the facts, on which some doubt had been |
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cast. In the isolated seeds of Cordaitales and Pteridosperms, |
cast. In the isolated seeds of Cordaitales and Pteridosperms, |
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pollen-grains are often found within the pollen-chamber, and the |
pollen-grains are often found within the pollen-chamber, and the |
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representatives from the latest Palaeozoic horizons. |
representatives from the latest Palaeozoic horizons. |
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{| |
{|{{Ts|ma|width:565px}} |
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|[[Image:EB1911 Palaeobotany - Cordaianthus.jpg|350px|center]] |
|[[Image:EB1911 Palaeobotany - Cordaianthus.jpg|350px|center]] |
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|{{sm|(All after Renault.)}} |
| {{sm|(All after Renault.)}} |
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|{{Ts|ac}}|{{sc|Fig.}} 32.—''Cordaianthus''. |
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A, ''C. Williamsoni |
A, ''C. Williamsoni''. Part of longitudinal section of ♀ catkin; 𝑎, |
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axis, showing |
axis, showing 𝑣, bundles in tangential section; 𝑏𝑟, bracts; 𝑑, short |
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axillary shoot, bearing a bracteole and a terminal ovule; |
axillary shoot, bearing a bracteole and a terminal ovule; 𝑖, integument; |
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𝑛, nucellus of ovule; 𝑜𝑣, another ovule seen from the outside. |
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( |
(✕ about 10.) |
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B, ''C. |
B, ''C. Grand’ Euryi''. Nucellus of an ovule; 𝑝.𝑐., pollen-chamber; |
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𝑠, canal leading to 𝑝.𝑐.; 𝑝, pollen-grains in 𝑝.𝑐.; 𝑝′, do. in canal. |
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( |
(✕ about 30.) |
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C, ''C. |
C, ''C. Grand’ Euryi''. Lower part of canal, enlarged; 𝑜, cavity of |
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canal, surrounded by a sheath of cells, dilated towards the bottom |
canal, surrounded by a sheath of cells, dilated towards the bottom |
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of canal, in which a large pollen-grain is caught; |
of canal, in which a large pollen-grain is caught; 𝑒𝑥, exterior of pollen grain; |
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𝑖𝑛, internal group of prothallial or antheridial cells. (✕ 150.) |
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D, ''Cycadinocarpus augustodunensis''. Upper part of seed, in longitudinal |
D, ''Cycadinocarpus augustodunensis''. Upper part of seed, in longitudinal |
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section; |
section; 𝑖, integument; 𝑚𝑖, micropyle; 𝑛, remains of |
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nucellus; |
nucellus; 𝑝.𝑐., pollen-chamber (containing pollen-grains), with its |
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canal extending up to the micropyle; |
canal extending up to the micropyle; 𝑝𝑟, part of prothallus; |
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𝑎𝑟, archegonia. All figures magnified. |
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living plants. Their internal structure is sometimes admirably |
living plants. Their internal structure is sometimes admirably |
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preserved, so that the endosperm with its archegonia is clearly |
preserved, so that the endosperm with its archegonia is clearly |
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shown (fig. |
shown (fig. 32, D). It is a curious fact that in no case has an |
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embryo been found in any of these seeds; probably fertilization |
embryo been found in any of these seeds; probably fertilization |
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took place after they were shed, and was followed immediately by |
took place after they were shed, and was followed immediately by |
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belonged to Cordaitales, especially those seeds which had a flattened |
belonged to Cordaitales, especially those seeds which had a flattened |
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form, such as ''Cardiocarpus'', ''Cycadinocarpus'', ''Samaropsis'', &c. |
form, such as ''Cardiocarpus'', ''Cycadinocarpus'', ''Samaropsis'', &c. |
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Seeds of this kind have been found in connexion with the Cordaianthus |
Seeds of this kind have been found in connexion with the ''Cordaianthus'' |
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inflorescences; the winged seeds of ''Samaropsis'', borne on long |
inflorescences; the winged seeds of ''Samaropsis'', borne on long |
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pedicels, are attributed by |
pedicels, are attributed by Grand’ Eury to the genus ''Dorycordaites''. |
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Many other forms of seed, and especially those which show radial |
Many other forms of seed, and especially those which show radial |
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symmetry, as for example ''Trigonocarpus'', ''Stephanospermum'' and |
symmetry, as for example ''Trigonocarpus'', ''Stephanospermum'' and |
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in form to the vegetative leaves, but smaller; sunk in their parenchyma |
in form to the vegetative leaves, but smaller; sunk in their parenchyma |
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are numerous tubular loculi, containing large pollen-grains, |
are numerous tubular loculi, containing large pollen-grains, |
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which are pluricellular like those of Cordaites; the female fructification |
which are pluricellular like those of ''Cordaites''; the female fructification |
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had not yet been identified with certainty. The curious male |
had not yet been identified with certainty. The curious male |
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sporophylls may perhaps be remotely comparable to those recently |
sporophylls may perhaps be remotely comparable to those recently |
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discovered in Mesozoic Cycadophyta, of the group Bennettiteae. |
discovered in Mesozoic Cycadophyta, of the group Bennettiteae. |
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Some leaves of Cycadean habit (''e.g. |
Some leaves of Cycadean habit (''e.g. Pterophyllum'', ''Sphenozamites'') |
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occur in the Coal Measures and Permian, and it is possible that |
occur in the Coal Measures and Permian, and it is possible that |
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the obscure Coal Measure genus ''Noeggerathia'' may have Cycadean |
the obscure Coal Measure genus ''Noeggerathia'' may have Cycadean |
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affinities. A fructification from the Permian of Autun, named |
affinities. A fructification from the Permian of Autun, named |
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Cycadospadix milleryensis by Renault, appears to belong to this |
''Cycadospadix milleryensis'' by Renault, appears to belong to this |
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family. |
family. |
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''Ullmannia'' and ''Pagiophyllum'', all of which resembled certain |
''Ullmannia'' and ''Pagiophyllum'', all of which resembled certain |
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Araucarieae in habit. In the case of ''Walchia'' there is some evidence |
Araucarieae in habit. In the case of ''Walchia'' there is some evidence |
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as to the fructifications, which in one species (''W. |
as to the fructifications, which in one species (''W. filiciformis'') |
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appear to be comparable to female Araucarian cones. There |
appear to be comparable to female Araucarian cones. There |
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are also some anatomical points of agreement with that |
are also some anatomical points of agreement with that |