[FlorenceArt]

Originally Posted by beppe

I did not find anything in my books but I found this in the net

Pittosporum tenuifolium

Spoiler:

In its native New Zealand, where it is known by the Maori names kohuhu or kohukohu, Pittosporum tenuifolium is an evergreen tree reaching to about 10m or so in height with almost black branches. The elliptic, glossy leaves are a rather pale green and usually have a wavy margin. The late spring flowers are small and a dark brownish-purple colour so they are not very showy but they have a delicious honey scent, especially in the evening. Plants can be found with hermaphrodite flowers, or separate male and female flowers or with male or female flowers only. Some cultivars are very similar and only readily distinguished by the sex of the flower. The species grows wild in the coastal and lower mountain forests of both the North and South islands up to an altitude of 900m. Pittosporum tenuifolium is sometimes grown under the cultivar name ‘Nigricans’ because of its black stems.
Some botanists have included the larger P. colensoi as a subspecies of P. tenuifolium. Its larger and more leathery leaves with a paler midrib and a more or less flat margin distinguish this species. It also grows on the North and South Islands from sea level to about 1000m. Many plants in cultivation appear to be hybrids between these two species.

How to use hardy Pittosporum in the garden (there is a reference to pots)

Spoiler:

P. tenuifolium and its cultivars and hybrids grow well in any fertile, well-drained soil in the milder areas of the UK, especially in the south and west and also thrive in coastal areas. In colder gardens, they may be grown in a sheltered position or on a south or west-facing wall. They make good specimen plants and the smaller cultivars such as ‘Peter Pan’ and ‘Pompom’ can be grown in containers for patio decoration.
They respond well to clipping making useful hedging plants and if necessary can be pruned back hard. The smaller leaved types can also be used for topiary. Some of the larger cultivars will make an effective evergreen screen. Variegated cultivars will lighten up a dark corner, especially ‘Irene Paterson’ with white-spotted foliage. The foliage of coloured and variegated cultivars may change through the year. The leaves of many purple-leaved cultivars for example, emerge green contrasting with the dark purple of the mature leaves while many yellow-leaved plants become greener as they age.
Many plants have black or very dark stems and these make a good foil for the foliage. Cut branches are very long- lasting in water, making this a useful floristry plant. The paler green and more crinkled leaves are most popular and some cultivars are grown commercially for this purpose in Cornwall, Ireland and The Netherlands.
Many cultivars and hybrids have been raised as chance seedlings, deliberate crosses or sports resulting in a wide selection of leaf variation and plant size for different positions in the garden. The best of these have been given the Award of Garden Merit as good, reliable, garden plants.

I found somewhere else that yours should flower in the Autumn.

I got the information here

Thank you Beppe! I'm reading the pdf file of your link and it says that 'Green Elf' is a dwarf (whew) male(!) plant. It also confirms that it grows best in mild climates, especially coastal areas. I'm not sure it will like the winter in Montreuil, but hopefully the worst of the weather is past for this year and it will last at least until next winter! I do hope they last longer because they look really pretty and are exactly what I was looking for.