Manual of Cultivated Conifers: Hardy in the Cold- and Warm-Temperate Zone

531 Pages·1978·25.793 MB·English

by  P. Den Ouden (auth.)

MANUAL OF CULTIVATED CONIFERS
FORESTRY SCIENCES
Also in this series:
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Bonga JM and Durzan DJ: Tissue Culture in Forestry. 1982.ISBN 90-247-2660-3
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MANUAL OF
CUL TIV A TED CONIFERS
HARDY IN THE
COLD- AND WARM-TEMPERATE ZONE
by
P. DEN OUDEN
former nurseryman at Boskoop (Netherland~)
in collaboration with
DR. B. K. BOOM
horticultural taxonomist at Wageningen (Netherlands)
•
:
~
.
. .
THE HAGUE / MARTINUS NIJHOFF / 1965
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The Netherlands
Library of Congress Cataloging in Publication Data
Ouden, P. den (Pieter den), 1874-1964.
Manual of cultivated conifers.
(Forestry sciences ;
Includes indexes.
1. Ornamental conifers. 2. Conifers.
3. Ornamenta~ conifers--VQrieties. 4. Conifers-
Varieties. I. Boom, B. K. (Boudewijn Karel),
1891- II. Title. III. Series.
SB428.C8 1982 635.9'752 82-12620
ISBN-13: 978-90-247-2644-8 e-ISBN-13: 978-94-009-9759-2
DOl: 10.1007/978-94-009-9759-2
Third edition 1982
Copyright © 1982 by Martinus Nijhoff / Dr W. Junk Publishers, The Hague.
All rights reserved. No part of this publication may be reproduced, stored in a retrieval system,
or transmitted in any form or by any means, mechanical, photocopying, recording, or
otherwise, without the prior written permission of the publishers,
Martinus Nijhoff / Dr W. Junk Publishers, P.O.Box 566, 2501 CN The Hague, The Netherlands.
CONTENTS
Preface
VII
The Conifers, General Review IX
Dwarf and Low-Growing Conifers XI
Short Nomenclatorial Note XII
Manual
Seed Density and Germination 473
The most Important Diseases and Pests of Conifers and Their Control
(J. Zwartendijk, Boskoop) 479
Forests, Trees, Timber and Man (W. Boerhave Beekman, The Hague) 487
Picture Credits 492
Abbreviations of Literature References 494
Index of Species Synonyms 498
Index of Synonyms of Varieties, Formae and Cultivars 504
I ndex of Vernacular and Trade-Names 5 I 6
PREFACE
As an introduction to the present book I would like to explain how it was, that I,
a commercial nurseryman, became so keenly interested in Conifers and their nomen
clature.
In August 1924 the Dutch Dendrological Society was founded and at the same time
a Committee for Nomenclature of woody plants was set up and I served on this
committee as one of the members. Our first activity was to bring the catalogues of
the various leading nurserymen in the Netherlands into line with the International
Rules of Botanical Nomenclature and also to check their nursery stock. Formerly
these catalogues had shown a rather confused nomenclature, nurserymen having
usually made use of a variety of inconsistent books as guides in compiling their
catalogues. In the course of the work a close co-operation between scientific and
practical workers developed. Although I had also fully contributed to the correct
naming of hardy shrubs and perennials, 1 was most interested in Conifers. I had
tried out several species, had grown a wide choice of garden forms and selected
types of particular merit for propagation. My special love for Conifers lead to the
publication of my Name-list of Conifers (1937), which was adopted as a standard
for varietal names at the International Horticultural Congress in Berlin (1938). Later
I prepared my book 'Coniferen, Ephedra en Ginkgo' in the Dutch language (1949);
compiling the Conifers cultivated or known to be grown in the Netherlands and
Belgium at that time.
As a result of my issuing this publication, English and American friends suggested
translating this book into English. With my decision to tackle this task, I also decided
that in this work I would attempt to give a description of most of the species, varieties
and cultivars which were known to me from personal experience or from the literature
as occurring in cultivation, or also lost or unknown to the trade. This means that
the total numbers have been very much increased. For practical purposes
I have confined the text to the Conifers hardy in the cold and warm temperate
zones, so that tropical Conifers are nearly all excluded. There are now 303 species,
208 varieties and formae 1935 cultivars dealt with in the text.
Because of my age I was not able to finish the work; I found Dr. B. K. Boom, Wagenin
gen ready to take up this work once more and he is responsable for the nomenclature
and the text of the novelties introduced since about 1955.
Many friends have greatly assisted me; I am, in particular, very much indebted to
the late Mr H. W. Renkema, assistant of the Arboretum of the Agricultural Univer-
VIII Preface
sity, Wageningen, who spared no pains in searching for the descriptions, examining
monographs and other literature.
Mr J. Lewis, taxonomist at the Botanical Department of the British Museum,
London, read the English text and lowe him a great debt of gratitude for the cor
rections he made.
Boskoop, June 1964 P. den Ouden t
It was a great pleasure for me to have the opportunityoffinishingthework of the lateMr.
P. den Ouden, who was always diligent in writing down his wide practical knowledge
of the Conifers. I had already assisted him for many years in nomenclatorial questions
and I was able to bring the names in accordance with the International Code for
the Nomenclature of Cultivated Plants (1962). We have inserted all the names of
cultivars published since 1753, in cultivation or not, with references to the literature,
so this book gives a survey as complete as possible of the cultivated Conifers which
serve as a basic list for the international registration of cultivarietal Conifer
names which is going to be established. All comments will be gratefully received at
the following address:
Wageningen B. K. Boom
P.O. Box 16
THE CONIFERS
General Review
The name 'conifer' is derived from the Latin conus, cone, and ferre, to bear, i.e.,
'bearing cones'. Although the Junipers and the Taxads (Yews) do not bear typical
cones, they are such a conspicuous feature, that the whole class together has been
called Conifers or Cone-bearers. These plants are mostly 'evergreen', meaning that
they retain their foliage when dormant, although some of them are annually leaf
shedding (the larches and the Bald-cypressus), the whole group of Conifers is often
popularly known as 'Evergreens'. Conifers belong to the Gymnosperms. The seeds
are naked, that is, they are not enclosed in a more or less closed container as in the true
fruits of the Angiosperms. The flowers of Conifers are produced separately, either
on the same tree (monoecious) or on different trees (dioecious). The male flowers
consist of a number of stamens, arranged in catkin-like clusters. The female flowers
are born in cones, each flower usually consisting of a bract and a scale; the bract
is sterile, the scale fertile and bears one or more seeds on its axil. In Juniperus
the scales are coalesced into a more or less soft berry-like fruit; the Yews have a
fleshy organ, the aril, which surrounds the seed; Podocarpus and Saxegothaea a part
of the floral axis which bears the scales, may become more or less fleshy as well as
the seed. The seeds are enclosed in a leathery or horny integument; they vary much
in size and shape in the different genera and in most cases a membraneous wing aids
in their dispersal by the wind. The leaves are either spirally arranged, scattered
or in decussate pairs, often decurrent at the base, solitary or on short spurs in fascicles
of 2,3 or 5 enclosed by a basal sheath (Pinus). They vary considerably in appearance:
scale-like on leaf-like branches (Phyllocladus); ovate and leathery (Agathis); needle
like (Pinus, Taxus); needle-like and scale-like leaves on the same plant are produced
by Cupressaceae; double-leaves occur in Sciadopitys.
The existing genera and species are believed to have developed in the course
of ages from others long since extinct. The evidence for this comes chiefly from the
fossil remains found in the different strata of which the crust of the earth is
composed. The remains indicate that Conifers were once spread far into the
Arctic regions. Geologists have shown that the distribution of land and water
has not always been the same as it is today, and that in earlier periods there
must have been a connection between the present-day continents in the far North.
Species of Sequoia, Sequoiadendron, Thuja and Cupressus have been found in
North Greenland; Pines, Spruces, Firs and Cupressus in Spitzbergen. It is reason
able to infer that the northern hemisphere underwent a change in climate. At
x Conifers-General
first it was of a tropical or sub-tropical character, later it became gradually
more temperate and passed into an extremely cold phase, when snow and ice ex
tended from the Arctic regions into the centre of Europe and North America. Under
this influence the Conifers were eliminated. As the ice-sheet receded northwards the
former sub-tropical vegetation was replaced by an arctic and sub-arctic flora which
included but few coniferous species although these spread over large areas.
This paucity of species has remained unchanged, except by the agency of man. The
changes wrought by man have been considerable for conifers and are due to
their great commercial importance. Whilst the coniferous vegetation of the northern
regions of the continents was thus affected by the glacial periods, the flora of the
Mediterranean region, China, Japan, North America west of the Rocky Mountains
and (on the east-side) south of the 39th parallel were exceptionally rich in coniferous
genera and species, as they are still.
Much less is known of the geological changes that have taken place in the south
temperate zone. In New Zealand Conifers reach their maximum representation in the
southern hemisphere. In Chile a considerable part of the slopes of the Andes is
covered with coniferous vegetation. In the tropical regions of both hemispheres
Conifers form but a minute fraction of the total arborescent vegetation.
DWARF AND LOW-GROWING CONIFERS
The term 'Dwarf Conifer' is used to denote two kinds of conifers, both artificial
dwarfs and natural dwarfs. The Japanese gardeners are experts in dwarfing by annual
pruning, pinching and disbudding, but only as long as these plants remain in their
pots, do they maintain their dwarfed habit. They also produce dwarfs by grafting on
uncongenial understocks; such dwarfs can be planted out of their pots with a good
chance of retaining their dwarfed habit. For outdoor gardening, however, artificial
dwarfs are generally not suitable. Natural dwarfs occur in several ways: they may
be self-sown seedlings in the wild or they may originate in the seed-beds of nurseries;
such forms as a rule retain their habit, and specimens are known which have fully
maintained their dwarf form after 80-100 and even more than ISO years. Furthermore
they may originate from sports or fasciations of an otherwise normal tree; these
forms easily revert to normal. Finally, they may spring from the conglomerations
of branchlets known as witches' brooms; such forms are tender and lose in time
their characteristics, especially when grafted.
Although some dwarfs do not exceed a height of 0.30-0.50 m, slightly taller forms,
up to 2.5 m, are also referred to as low-growing conifers, to distinguish
them from the tall-and very tall-growing forms of the same age. For instance, Chamae
cyparis obtusa 'Nana Gracilis', the much grown and desirable Japanese Dwarf Cypress
will reach in 30-40 years a height of about only 2 meters; really dwarf is Chamae
cyparis obtusa 'Nana'; plants of this form, more than 100 years old, will reach about
one meter. Dwarf and low-growing conifers are excellent plants for many situations;
for foundation plantings, for growing in front of taller species or varieties and for
the small gardens of the present day, in which space is much restricted. There was
a time when but little attention was given to these small forms, but with an increased
interest in rock-gardens, the surroundings for which they are most suited, there is
a much increased demand for dwarfs. Loudon (1838) mentioned only 10 dwarf
forms; Carriere (1867) recorded about 40, Beissner (1909) found about 150. Murray
Hornibrook became the first author to collect in one book the many forms re
corded in the literature or known in cultivation, and to revise their nomenclature,
adding a large number of new forms. His 'Dwarf and Slow-growing Conifers'
(1923), revised and enlarged in 1939, is still the standard work on this subject
and testifies to his skill in tracing and rediscovering old forms; he records abuot
500 in all. In the present work, the number of dwarf and low-growing cultivars is
once more increased.