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Recommended Books

A Field Guide to the Native Edible Plants of New Zealand

A practical field guide to New Zealand's native edible plants. Andrew Crowe

Gardener's Encyclopaedia of NZ Native Plants

 Gardener's Encyclopaedia of NZ Native Plants by Cave, Paddison

Trees and Shrubs of New Zealand

 Trees and Shrubs of New Zealand  by Poole and Adams

The Reed Field Guide to New Zealand Native Trees

 The Reed Field Guide to New Zealand Native Trees by J.T. Salmon

Which Native Plant Can I Grow Here?

100 Best NZ Native Plants for Gardens

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High Altitude Mountain Daisies (Celmisia Semicordata), Mt Cook NP, Canterbury, New Zealand
High Altitude Mountain Daisies (Celmisia Semicordata), Mt Cook NP, Canterbury, New Zealand
McCormack, Gareth
18 in. x 24 in.
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Monoecious and dioecious plants.

Coprosma lucida female
Coprosma lucida female

Coprosma lucida male
Coprosma lucida male
 

One of the intriguing features of the New Zealand flora is the high percentage of plants that have separate male and female individuals. While this is the norm in animals, plants that have male and female sex organs on different individuals is unusual.
Male flowers are those whose gametes (pollen) leave the flower, while female flowers are those whose gametes (ova) remain in the flower and are receptive to the male gamete.

Monoecious plants have the 2 sexes on the same plant, with all individuals producing male pollen and female eggs and seed. Monoeciousness is the norm in most plants of the world.
Some monoecious plants can be classed as hermaphrodite with flowers which contain both male and female parts.
In many hermaphrodite flowers there is a time when the flower is male with anthers distributing pollen, and a time when they are female, with a receptive stigma. By timing their sex expression the plant increases the likelihood of being pollinated by another member of the same species. The pollen would not be shed when the ovary was ripe. Usually the female stigma is receptive after the pollen is shed.  Outcropping or fertilization by another member of the same species is encouraged, which enhances variety within the species
Monoecious plants have separate male and female flowers found on the same plant. The same idea of timing the male and female functions to maximize the chance of cross pollination occurs but the likelihood of self pollination is increased.

 

 


Dioecious plants have male and female flowers on separate plants. Exotic plants that this occurs in include Kiwi fruit and Cannabis sativa which have male and female plants. A characteristic of the The New Zealand flora is the high % of plants that have the sexes on separate plants (dioecious). Approx 12-13% of our flora are dioecious. (Britain 2-5%, South Australia, 3.9%., Hawaii 5%). However in any plant association there may be up to 50% of the individuals who exhibit dioeciousness
The significance of dioeciousness  to the propagator of seeds is that female plants need to be sourced if seed is to be collected.
Dioeciousness of plants account for the variability in seeding from year to year that some species exhibit because seeding will be determined by synchronising the time at which the male and female parts are functional. Rimu may go 7-12 years before seed on females is produced in abundance. These years are termed mast years.
As a male tree may be some distance from a female tree, the environmental conditions that determine flowering would be more variable in separate trees than the same tree. There is more likelihood of reproductive failure if the nearest tree of the opposite sex is some distance away. The fact that pollen from a distant tree must fertilise a female tree may put the successful reproduction and production of viable seed under stress. Logging of a population, and a reduction in total density of the adult trees and total gamete production will reduce the likelihood of fertilisation . This seems to be the case in Monoao( Dacrydium kirkii), a dioecious species of conifer that grows in Northlands kauiri forests.Monoao has become relatively rare in the wild with its natural range vastly reduced to remnant populations in Coromandel, Northland and Little Barrier Island.

The ratio between the number of plants of a species that are male or female will influence the availability of seed of the dioecious species.

If a plant is grown for the beauty of its seeds (Porokaiwhiri) or flowers (Clematis) growing from seed will produce some individuals who are not of the desired sex. In these cases reproduction by cutting is suggested.

A significant excess of males or females may exist in natural populations. Usually Coprosma have more males than females in their populations.

A feature related to separate male and female trees is Sexual dimorphism. This is that male plants have different form or shape than females. Of course in most animals this is obvious with the male having a different body shape to females. In plants however it is less obvious but does exist. Male Coprosma show broader leaves to female Coprosma.

 

 
Other useful links : Germination strategies     A New Zealand garden   Native Grasses   Cultivation Guide    Divaricating plants    Juvenile & Adult Forms     Dioecious plants      NZ Botanists & plant names         Proverbs & quotes      Special features     Photographs    Information for identification

Life-size Guide to New Zealand Native Ferns: Featuring the Caterpillars Which Feed on ThemA Field Guide to the Native Edible Plants of New ZealandGardener's Encyclopaedia of NZ Native PlantsTrees and Shrubs of New ZealandThe Reed Field Guide to New Zealand Native Trees

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Species list for information on native plants

Agathis australis       Alectryon excelsa     Alseuosmia banksii Aristotelia serrata    Arthropodium cirratum Beilschmiedia tarairi Beilschmiedia tawa  Brachyglottis repanda Carmichaelia    Carpodetus serrata Coprosma          Cordyline australis     Cordyline banksii.  Corynocarpus laevigatus    Cyathodesfasciculata    Dacrydium cupressinum  Dacrydium kirkii         Dianella nigra     Dodonaea viscosa Dysoxylum spectabile Elaeocarpus dentatus    Elingamita johnsonii  Entelea arborescens    Fuchsia excorticta     Fuchshia procumbens  Gaultheria               Geniostoma ligustrifolium Hebe  Hedycarya arborea               Hoheria populnea    Kunzea ericoides   Laurelia novae zelandiae     Lophomyrtus  Libocedrus plumosa Leptospermum scoparium            Knightia excelsa    Macropiper excelsum Meryta sinclarii    Melicope ternata Melicope simplex    Melicytus ramiflorus          Metrosideros excelsa  Myoporum laetum    Myrsine australis    Nothofagus       Phormium tenax Phyllocladus trichomanoides    Prumnopitys    Pittosporum          Pisonia brunonnianum   Podocarpus dacrydioides         Pratia physaloides  Pouteria costata      Pseudopanax    Pseudowintera colorata          Pomaderris kumaraho  Rhabdothamnus solandri        Rhopalostylis sapida    Rubus                 Schefflera digitata    Solanum aviculare    Sophora microphylla    Tecomanthe speciosa  Toronia toru            Vitex lucens    Weinmannia

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